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

With no annotations, the description carries the full burden and does reasonably well: it discloses the return payload (captions, media URLs, like/comment counts, cursors), the pricing model (per page, 1 credit per page, defaults to 1 page), and the required Authorization: Bearer header. It omits rate limits, error behavior, and post ordering/recency semantics, keeping it short of a 5.

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 payload description is front-loaded and useful, but pricing is stated twice ('Priced per page; defaults to 1 page' and 'Costs 1 credit(s)... Credits unit: page'), and a stray double period plus machine-generated metadata fields add noise. It earns its place but is not tight.

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 read-only fetch tool with no output schema and no annotations, the description covers what an agent needs to call it: resource scope, returned fields, auth, and cost model. Only rate limits and pagination termination behavior are unaddressed.

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 100%, so depth, user_id, chunk_size, and start_cursor are already documented with examples and defaults. The description only reinforces the page/credit relationship and pagination cursors, adding little beyond the schema — the baseline 3 for full coverage 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?

States a specific verb and resource ('Fetch recent public posts for a user id'), which clearly separates it from a single-post sibling like instagram_post. However, it never names or contrasts with any sibling, leaving the agent to infer the posts-vs-post distinction from the tool names alone.

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?

There is no explicit when-to-use statement, no prerequisites beyond the auth header, and no guidance on choosing between this and instagram_post, instagram_detailed, or instagram_tagged. Usage is only implied by 'for a user id'.

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