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

Beyond the readOnly/openWorld annotations, the description discloses two things annotations cannot: the logged-out visibility limitation (so private or restricted data is out of scope) and the x402 payment model at $0.05 USDC per successful call on Base or Solana. That cost/auth context is exactly the kind of behavioral detail an agent needs before invoking. It does not cover failure or refund behavior, so not 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?

Two dense sentences with the returned fields front-loaded, followed by the scope limit and the pricing clause. Almost nothing is wasted, though the second sentence is a fragment and the pricing note could be tighter.

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 correctly compensates by enumerating the returned fields, and it adds the paid-call model. Remaining gaps are minor for a single-parameter read tool: no mention of behavior for nonexistent or private handles, and no rate-limit or retry context.

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 parameter is already documented as 'username (with or without the @) or instagram.com profile link'. The description's phrase 'for a username or profile link' merely restates that, adding no syntax, normalization, or validation detail. 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?

States a specific resource (the public Instagram profile page) and enumerates exactly what is returned: full name, bio, picture, verified/private flags, follower/following/post counts, numeric user ID. An agent knows precisely what it gets. It does not explicitly distinguish itself from the sibling instagram_name_search, so it stops short of a 5.

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?

Usage is implied: supply a handle or profile link and receive profile data. The clause 'Only what Instagram shows logged-out visitors' usefully bounds expectations, but there is no explicit statement of when to prefer this over instagram_name_search or username_scanner, and no prerequisites beyond the payment note.

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