---
title: "How to Build an Agent-Facing SDK Compatibility Matrix"
description: "How to build an SDK compatibility matrix that gives coding agents one clear route to the right version, auth path, and runnable example, then test and revise it with real coding-agent tasks."
url: "https://www.withgauge.com/resources/how-to-build-agent-facing-sdk-compatibility-matrix/"
author: "Farbod Memarian"
published: "2026-10-06"
---

# How to Build an Agent-Facing SDK Compatibility Matrix

## TL;DR

- A compatibility matrix gives a coding agent one clear route to the SDK version, authentication path, and runnable example that fit its task and repository.
- Each route should state supported versions, runtime and dependency limits, migration status, unsupported combinations, and a direct example link.
- Build the matrix, then test it with real coding-agent tasks. Inspect the chosen package and final code, revise ambiguous routes, and rerun the same tasks.
- Gauge Agents lets you run those tasks in isolated repositories and inspect the agent's choices and final code.

## Why a generic compatibility chart fails coding agents

A chart that marks a language and SDK version as "supported" leaves out the decision a coding agent needs to make. The agent also needs to know whether that version works with the repository's runtime and dependencies, which authentication path applies, and which example matches the task. An SDK can install successfully while the agent still leaves code that cannot complete the intended integration. [Agent Experience](https://www.withgauge.com/blog/agent-experience/) treats working, verified code as the goal.

The task prompt, repository, and documentation can each point an agent toward a different SDK version. For example, `AGENTS.md` may require one version while the package manifest lists another. If both matrix rows say only "supported," the agent still has no documented rule for resolving the conflict. Account for these inputs when you [test how agents choose tools](https://www.withgauge.com/resources/how-coding-agents-choose-developer-tools-2026/).

An agent-facing matrix should connect each supported route to the task and repository conditions that make it valid. It should also name the correct authentication path and link to a runnable example. You can then test a representative repository task to see whether an agent fetched the matrix, chose the intended route, and produced working code.

## What belongs in an agent-facing compatibility matrix

A compatibility matrix should let you match a repository and task to one supported integration path. Give each row a specific use case, then put the constraints before the example link. [Gauge's agent documentation guidance](https://www.withgauge.com/blog/what-makes-good-agent-documentation/) recommends stating version and environment limits before the steps that depend on them.

The table uses a fictional package, illustrative version constraints, and example-link placeholders. Replace each `EXAMPLE_URL` placeholder with a direct link to a runnable, version-specific example before publishing your matrix.

| Task and language | SDK and version | Runtime and dependencies | Auth and credential handoff | Migration state | Unsupported combination | Canonical example URL | Verification |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Send an event with ExampleLang | `@example/widget` 2.x | Node.js 20+, helper 3.x | Read `EXAMPLE_API_KEY` from an environment variable | Supported for new server integrations | Edge runtime with 2.x | `EXAMPLE_URL_V2_SERVER` | Run `npm test` and check for an accepted event |
| Maintain an existing ExampleLang integration | `@example/widget` 1.x | Node.js 18+, helper 2.x | Read `EXAMPLE_API_KEY` from an environment variable | Supported for existing integrations; migrate to the 2.x server route for new work | Edge runtime with 1.x | `EXAMPLE_URL_V1_LEGACY` | Run `npm test` against the existing integration |
| Send an event from an edge runtime | No supported package version | Edge runtime | Not applicable | Unsupported; move event sending to a Node.js 20+ server using 2.x | All listed edge combinations | `EXAMPLE_URL_V2_SERVER` (server alternative) | Run the server example's test and check for an accepted event |

Use the task and constraint columns to separate an existing integration from a new one. The auth column should specify how the code receives credentials without putting secrets in source files. For an unsupported row, name the required change and link to the supported alternative; for a legacy row, say whether the existing integration can remain in use.

Each supported row needs its own complete example, not a link to a generic quickstart. Include the install command, imports, setup, authentication, API call, error handling, and observable output. Keep the example's package version and verification command consistent with its matrix row so you can check the chosen route in the repository.

## Making the correct route unambiguous

The matrix needs a rule for resolving competing repository signals, not an assumption that `AGENTS.md` always wins. Check its instructions against the package manifest and lockfile, then match the installed versions, runtime, authentication path, and requested task to a row. If those signals conflict, state which route requires a migration and link to its steps. [Repository rules and installed dependencies](https://www.withgauge.com/resources/how-coding-agents-choose-developer-tools-2026/) are inputs to the decision, not substitutes for that rule.

Mark a default when multiple supported rows still match, and state when to choose each alternative. If the lockfile pins SDK v1 but the task requires a v2-only feature, specify the migration steps and required runtime or dependency changes before directing the agent to the v2 example. Do not let "latest version" silently override a pinned version. If no supported route exists, say so rather than implying that a replacement is always available.

Link the matrix beside installation and authentication steps in setup pages and quickstarts, and include it in READMEs. These pages appeared among the [documentation fetched in Gauge's observed agent runs](https://www.withgauge.com/resources/what-documentation-do-coding-agents-fetch/). Add the matrix to the [llms.txt routing index](https://www.withgauge.com/blog/how-to-write-a-good-llms-txt-file/) as another way to find it, but keep the actual decisions on the matrix page.

## Documenting version-specific examples and migration paths

Keep legacy versions in the matrix while repositories still use them. Mark each route as supported, deprecated, or unsupported, and give supported or deprecated routes their own version-specific examples. For an unsupported route, name the incompatible constraints and link to a supported alternative if one exists. A legacy example should use the package and API named in its row so the agent can apply it to the older repository.

Give deprecated rows a migration path, and give unsupported rows a replacement when one exists. For the fictional SDK, an unsupported Node.js 16 route could specify Node.js 20 and SDK v2, then link to the example for that combination. A deprecated SDK v1 row should say whether the existing integration can keep running during migration. Avoid "see latest docs," which leaves the version choice unresolved; state constraints before linking to the example that meets them, as [Gauge's documentation guidance](https://www.withgauge.com/blog/what-makes-good-agent-documentation/) recommends.

Put renamed APIs and their replacements near the top of each affected page. If you publish both Markdown and HTML versions, keep the version ranges, install commands, migration status, and example links consistent across them. [Guidance on serving Markdown to agents](https://www.withgauge.com/blog/serve-markdown-to-ai-agents/) calls for current version details and API replacements near the top, where a reader can check them before following an outdated example.

## Testing the matrix with representative coding-agent tasks

Test the matrix with coding tasks in isolated repositories whose expected routes you have defined in advance. Include a repository ready for the current SDK, one pinned to a legacy version, and one with a combination the matrix rejects. Ask the agent to implement the integration where a supported route exists; for the rejected combination, ask it to use the documented alternative or report that none exists.

Define success before each run. For the current path, name the expected package version, authentication method, runnable example, and verification command. For the legacy path, specify whether the agent should keep the supported older version or migrate to its replacement. For the unsupported combination, specify whether the agent should choose a documented alternative or stop without adding incompatible code.

Inspect the [agent trace](https://www.withgauge.com/blog/agent-experience/) as well as the final repository. Record what the agent searched for and which pages it actually fetched, since a search result does not show that the agent read the matrix. Then check the package and version it installed, the credential flow it used, and the code diff. Run the predefined verification check against the final code. A fetched matrix or a successful install cannot, on its own, establish that the agent chose the right route.

If a run takes the wrong path, change one ambiguous matrix row or its linked example. Rerun the [same task with the same agent, model, and starting repository](https://www.withgauge.com/resources/agent-led-growth-strategy-repeatable-growth-loop/), changing only the documentation under test. Then compare the traces and verification results. A matched rerun can show whether that edit helped in the tested case. One successful run does not establish how other agents or repositories will behave.

## Revising the matrix from what the trace shows

A trace should point you to a specific row or example to fix. If the agent fetched the matrix but chose an outdated SDK, check whether the row names the supported version for that task and repository. If it chose the right version but used the wrong credential, clarify the authentication path beside that row and link to the matching runnable example.

If the agent never fetched the matrix, fix the path to it before rewriting a row. Check which setup page or README it opened and link the matrix where that route decision arises. If the agent fetched the matrix but made the wrong choice, use its package changes, code diff, and verification result to identify the row or example that needs work. [Gauge's testing guidance](https://www.withgauge.com/blog/what-makes-good-agent-documentation/) describes this distinction between finding documentation and using it correctly.

After fixing a row or entry point, rerun the same task with the same agent, model, and starting repository. Compare its trace and verification result with the baseline to see whether the agent found the matrix, chose the intended route, and completed the integration. [Repeat the test](https://www.withgauge.com/resources/agent-led-growth-strategy-repeatable-growth-loop/) before treating one successful rerun as a reliable fix.

## Where Gauge Agents fits

Gauge Agents runs [real coding agents against real repositories in isolated environments](https://www.withgauge.com/blog/agent-experience/) and preserves traces for comparison across reruns. Use it to check whether an agent chooses the matrix route that fits the task and repository, rather than counting a documentation fetch as a successful integration.

In Gauge Agents, inspect the [searches, fetched pages, package changes, file writes, errors, code diffs, and final repository state](https://www.withgauge.com/resources/best-platforms-for-improving-documentation-for-coding-agents-2026/). Compare the selected SDK and authentication path with the expected matrix row, then run the repository's verification check. After a documentation edit, compare the new trace and result with the baseline to see what changed in that tested task.

## Conclusion

Treat the matrix as an Agent Experience resource that changes with the SDK. When you change version support, authentication, or migration guidance, update the affected rows and examples, then rerun the relevant coding-agent tasks. Verify the selected package, credential flow, and final code rather than stopping at a documentation fetch.

## FAQs

### How does the matrix differ from general agent documentation?

General [agent documentation](https://www.withgauge.com/blog/what-makes-good-agent-documentation/) covers setup, authentication, examples, and troubleshooting. The matrix answers a narrower question. Given a task and a repository, which supported SDK version, authentication path, and example should the agent use?

### How often should we retest the matrix?

Retest when you change SDK support, runtime requirements, authentication instructions, migration guidance, or a linked example. Run the affected tasks again in representative repositories. Keep the task, agent, model, and repository the same when you want to compare the new documentation with the previous version.

### What counts as an unsupported combination worth documenting?

Document a combination when its parts might look compatible but cannot work together, such as an SDK version that requires a newer runtime than the repository uses. Name the conflicting versions and give a supported route where one exists. Place that warning beside the affected row so the reader does not have to infer it from another page.

### Is one test run enough to trust a fix?

No single run establishes that a documentation change will work across repositories or tasks. Check whether the agent fetched the matrix, chose the intended package and authentication path, and left working code. Then repeat representative tasks and [compare the traces](https://www.withgauge.com/resources/agent-led-growth-strategy-repeatable-growth-loop/) before treating the fix as reliable.

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Full index of this site for agents: https://www.withgauge.com/llms.txt

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