post_image

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full behavioral burden. It discloses a critical behavior: Instagram fetches the image directly from a publicly reachable JPEG URL. This is valuable operational context, though it does not cover side effects, authentication, or failure modes.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tightly written sentences with no filler. The core action is stated first, and the critical URL constraint is front-loaded immediately after.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a low-complexity, two-parameter tool without an output schema, this description covers the essential operational details: what is published, where it is published, and how the image must be provided. Some potential details like auth or rate limits are absent, but the core usage is adequately specified.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It adds crucial meaning to image_url by specifying it must be a publicly reachable JPEG, which goes beyond the schema's plain 'format: uri'. The caption parameter is left to the schema, but the most important parameter is well explained.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource: 'Publish a single photo to the feed.' This clearly distinguishes it from sibling tools like post_story and post_reel, which target different formats and surfaces.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The phrase 'to the feed' and 'single photo' provides clear context for when this tool applies, especially alongside post_story and post_reel. It does not explicitly name alternatives or exclusions, but the intended use is clear enough for an agent to select it correctly.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.