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

No annotations are provided, so the description carries the full burden. It does disclose two operationally important facts — a 10-credit cost and the required Authorization: Bearer <api_key> header — plus that only public profiles are fetched. It says nothing about behavior for private, suspended, or nonexistent accounts, or about rate limits.

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?

Three short sentences, front-loaded with the core purpose and fields, with cost and auth trailing appropriately. Minor sloppiness: a doubled period after 'media..' and boilerplate 'Platform=instagram resource=detailed' phrasing.

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?

With no output schema, the description usefully enumerates the returned fields, which partly compensates. But for a paid, authenticated call sitting alongside a near-identical sibling, the absence of selection guidance and of error/private-account behavior leaves real gaps.

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 single 'username' parameter is documented in the schema as 'Instagram username without @'. The description only restates 'for a username' and adds no format or edge-case semantics beyond what the schema already provides.

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 (Fetch) and resource (full public profile for a username) and enumerates the returned fields: bio, follower/following counts, category, business fields, timeline media. However, it never distinguishes itself from the sibling instagram_user, which an agent would plausibly confuse with this 'detailed' variant.

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?

No when-to-use guidance is given. With instagram_user, instagram_followers, and instagram_posts all in the sibling set, the agent gets no signal about when this costlier detailed profile is preferable to those alternatives.

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