# Research a third-party API before integrating it in C with Atlas (2026)

> Atlas researches a third-party API before a C integration with websearch and webfetch, both permission-gated, so you write bindings against real signatures rather than remembered ones.

Atlas can leave the repo when the answer is not in the repo, which is exactly the situation when you are about to write a C binding against a library you have not used since 2019. Atlas's websearch finds the current documentation page, webfetch pulls it with format negotiation for markdown, text, or html, and both sit behind explicit permissions so the model cannot quietly send your headers to arbitrary hosts. You read the real function signatures, then write the integration against them instead of guessing, and verify with Unity via ctest after `make`.

## Key takeaways

- Atlas can leave the repo when the answer is not in the repo: websearch finds the page, webfetch pulls it.
- Atlas's websearch injects the current year into its description, so the model biases toward fresh C library docs rather than an archived manual.
- webfetch negotiates format, so passing markdown or text steers the server toward prototypes rather than navigation chrome.
- webfetch asks for permission with the URL as the pattern before any request goes out, so context is never quietly exfiltrated to arbitrary hosts.
- In C, a wrong ownership assumption is undefined behavior, not an exception, which is why the real prototypes matter more than remembered ones.
- Grep the existing .c and .h files for the project's own conventions before committing to an integration pattern.

## Why should I fetch API docs before writing a C integration?

In C, a wrong API assumption is not a runtime exception, it is undefined behavior. Guessing that a library function returns a heap pointer you must free, when it returns a pointer to static storage, produces a crash that appears three hours later. Atlas fetches the current docs in 2026 rather than recalling them.

C punishes guessing harder than any managed language, because the type system will not stop you. If a third-party function's ownership contract says the caller must `free()` the returned buffer and you assume otherwise, you leak. If it says the buffer is owned by the library and you free it, you corrupt the heap. If the error convention is a negative return code rather than `errno`, your error handling silently never triggers. None of these are caught by the compiler, and none are caught by a passing test that only exercises the happy path. Atlas's answer is to get the current shape of the external API into context before writing the integration, instead of guessing from memory. That means the real signatures, the real ownership rules, and the real error codes, pulled from the documentation as it exists now, not as the model remembers it.

## How do I find the current documentation page for a C library with Atlas?

Call Atlas's websearch to find the current documentation page. The websearch tool injects the current year into its description, so the model biases toward fresh sources rather than an archived 2019 manual page that documents a function signature the library changed two major versions ago.

Finding the right page is half the problem for a C library, because C documentation is scattered: a man page, a Doxygen-generated site, a header file in the tarball, and a decade of Stack Overflow answers describing an older API. Atlas's websearch injects the current year into its description, which biases the model toward fresh sources and away from stale ones. That matters when a library's error convention changed between major versions and every high-ranking blog post predates the change. Atlas searches your own repo separately, and it also indexes code by AST declarations using tree-sitter, so once you have the external docs you can compare them against the headers already vendored under `include/` or pulled in by Conan. websearch is for when you do not have the URL. When you do, go straight to webfetch.

## How does Atlas's webfetch pull an API reference page?

Fetch the page with Atlas's webfetch, passing format markdown or text so the Accept header steers the server toward a compact representation. webfetch supports 3 formats, markdown, text, and html. For a C API reference full of function prototypes, markdown gives you the signatures without navigation chrome.

Atlas's webfetch supports format negotiation for markdown, text, or html. The format you pass sets the Accept header, which steers the server toward a compact representation of the page. For researching a C API, that is a meaningful difference: an HTML docs page for a library reference can be mostly sidebar, while the markdown or text form is mostly prototypes, parameter tables, and return-value semantics. Fetch the reference page, read it, and extract the three things a C integration actually depends on: the exact function prototypes, who owns any returned pointer, and how errors are signaled. Then write the integration with Atlas's write or edit tools against those real signatures. Atlas computes a unified diff for every file edit and surfaces it for approval before writing, so the new `src/vendor_client.c` and its header arrive as a diff you review.

## Can an AI agent send my C source to arbitrary hosts?

Not with Atlas. Approve the webfetch permission prompt before any request goes out: the tool asks with the URL as the pattern, so you see the exact host before Atlas contacts it. Every Atlas tool call is permission-gated against allow, ask, and deny rules before it runs, and in 2026 webfetch is no exception.

Network access is the tool category where an agent could do the most quiet damage, so Atlas puts it behind an explicit gate. webfetch asks for permission with the URL as the pattern, which means the approval you give is scoped to a host you actually looked at, not to the internet in general. websearch is gated the same way. The design intent is stated plainly: both sit behind explicit permissions so the model cannot quietly exfiltrate context to arbitrary hosts. For a C codebase under export controls or a defense or embedded contract, that matters as much as the code quality. Atlas can also build its code index with local Ollama embeddings, keeping code off third-party servers, so the semantic index over your `src/` and `include/` trees is computed on your own machine while the docs research happens over an approved, named URL.

## How do I make a new C integration match the project's existing conventions?

Verify against the repo's own conventions with Atlas's grep before committing to a pattern that does not match the codebase. A C project has 3 house rules worth checking: how errors propagate, whether allocations go through a custom allocator, and whether every header carries an include guard or a pragma once.

Documentation tells you what the third-party API expects. Grep tells you what your own C codebase expects, and the integration must satisfy both. Before writing `src/vendor_client.c`, grep the existing sources for how other modules handle a failed allocation, whether the project wraps `malloc` in a project allocator, and how error codes travel back to callers. Atlas's grep takes a real regex plus include and path filters and runs through ripgrep, so scope it to `*.c` and `*.h` and skip the build directory. Write the integration with Atlas's write or edit tools against the real signatures you fetched, run clang-format so the new file matches the project's style, build with your Makefile, and run Unity via ctest. Let Conan resolve the library dependency rather than vendoring a copy by hand.

## Steps

1. Run atlas in the C project with a Makefile so it can see your headers, source files, and build rules.
2. Call Atlas's websearch to find the current documentation page for the third-party API. The tool injects the current year into its description, so the model biases toward fresh sources.
3. Fetch the page with Atlas's webfetch, passing format markdown or text so the Accept header steers the server toward a compact representation instead of navigation chrome.
4. Approve the webfetch permission prompt. The tool asks with the URL as the pattern before any request goes out, so you see the exact host first.
5. Read the fetched content and extract the three things a C integration depends on: the exact function prototypes, who owns any returned pointer, and how errors are signaled.
6. Verify against the repo's own conventions with Atlas's grep before committing to a pattern that does not match the codebase, for example how other modules handle a failed allocation.
7. Write the integration with Atlas's write or edit tools against the real signatures, reviewing the unified diff Atlas surfaces before it writes src/vendor_client.c and its header.
8. Let Conan resolve the library dependency rather than vendoring a copy by hand, and run clang-format over the new files.
9. Build with make and run Unity via ctest to confirm the integration behaves against the real API contract, not the remembered one.

## FAQ

### how do I get an ai agent to read current api docs before writing c code

Call Atlas's websearch to find the current documentation page, then webfetch to pull it, passing format markdown or text. Atlas's websearch injects the current year into its description so the model biases toward fresh sources.

### does atlas send my c source code to external websites

No. Atlas's websearch and webfetch sit behind explicit permissions so the model cannot quietly exfiltrate context to arbitrary hosts. webfetch asks with the URL as the pattern before any request goes out, so you approve the exact host.

### what format should I use with webfetch for api reference pages

Pass format markdown or text. The format sets the Accept header, which steers the server toward a compact representation. For a C API reference that means function prototypes and return-value semantics rather than sidebar navigation.

### why not just let the model recall the c library api from memory

In C a wrong API assumption is undefined behavior, not an exception. A remembered ownership contract that says free the returned buffer, when the library owns it, corrupts the heap. Fetch the current docs and write against the real prototypes.

### how do I make a new c module match my project's conventions

Grep the existing .c and .h files with Atlas before committing to a pattern: how other modules handle a failed allocation, whether the project wraps malloc, how error codes propagate. Documentation tells you the API's rules, grep tells you your own.

### how do I add a third party c library dependency

Let Conan resolve the library rather than vendoring a copy by hand, then build with your Makefile and run Unity via ctest. Atlas surfaces a unified diff for every file edit for approval before writing.

### atlas is asking permission to fetch a url

That is webfetch's permission prompt, which asks with the URL as the pattern before any request goes out. Approving it authorizes that host, not the internet in general, which is how Atlas keeps a C codebase from leaking to arbitrary servers.

### can atlas index c code without a third party service

Yes. Atlas can build its code index with local Ollama embeddings, keeping code off third-party servers, so the semantic index over your src/ and include/ trees is computed locally while docs research happens over an approved URL.

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