Post an Instagram image or carousel

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

The description goes well beyond annotations by disclosing that preview is the default and performs nothing, that apply:true is required to write, that a poll-timeout returns status=in_progress with resume_container_id, and that re-running must resume rather than create a duplicate. It also clarifies that Instagram validates image format and dimensions at fetch time, which is essential behavioral context.

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 compact and front-loaded: the first sentence states the primary action and workflow, and each following sentence earns its place by covering preview behavior, resume edge cases, and validation expectations. There is no repetition of schema content or filler.

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 7-parameter, open-world tool with no output schema, the description covers the key operational flow, the preview/write distinction, the resume path, and the duplicate risk. The main gap is that it does not describe what a successful publish or a preview response returns, which would help an agent handle results without an output schema.

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 coverage is 100%, and the schema already documents apply, imageUrls, resumeContainerId, and the duplicate-avoidance behavior. The description repeats and reinforces the workflow but does not add new per-parameter semantics beyond what the schema provides, so the baseline 3 is appropriate.

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 starts with a specific, scoped action: 'Publish a single feed image, or a 2–10 image carousel, in one call'. It clearly differentiates this from reel/story posting and from the lower-level container/publish siblings, so an agent knows exactly what resource this tool acts on.

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 this tool: for a single feed image or carousel, in one call, versus the alternative of manually creating containers and publishing. It does not explicitly name sibling tools or state when not to use them, so it stops short of a fully explicit routing guide.

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