publish_image

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

With no annotations, the description carries the behavioral burden and does well: it discloses that Instagram fetches the image bytes from the URL itself, which explains why the URL must be public, and that the two-step Graph flow is handled internally. This conveys meaningful operational behavior beyond the schema, though it omits details like failure handling or account selection.

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?

The description is three short sentences, each carrying distinct information: purpose, URL requirement, caption limit, and internal flow. It is front-loaded and free of filler, making it easy for an agent to parse quickly.

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?

An output schema exists, so return values are covered. The description addresses the main operational gotchas: public URL fetching, caption length, and the internal two-step Graph flow. The only notable gap is the account parameter semantics, but the optional nature with a default null and sibling account tools make this a minor deficiency.

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?

The schema has 0% description coverage, so the description must compensate. It effectively explains image_url (must be public https) and caption (<= 2200 chars), but it says nothing about the account parameter, such as whether null means 'use the default account.' One of three parameters remains undocumented in the description, leaving a partial gap.

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 action and scope: 'Publish a single image to the feed.' The word 'single' differentiates it from sibling tools like publish_video, publish_carousel, and publish_story, while 'feed' distinguishes it from publish_story. This is enough for an agent to select it correctly without opening schemas.

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 description gives clear context for when to use the tool: for a single image, not video or carousel. It also provides explicit preconditions, noting that image_url must be a public https URL and caption must be <= 2200 chars. It does not explicitly name alternative tools, but the scope constraints make the when-not condition clear.

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