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

Adds substantial context the annotations do not carry: the price ($0.02 per successful call), the x402/USDC-on-Base payment mechanism with the exact _meta key, and a billing policy that free-of-charge conditions include bad input and not-found. This is exactly the kind of cost and side-effect information an agent needs before invoking a paid, non-idempotent call.

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?

Front-loads the resource and returned fields, then closes with pagination and pricing — a sensible order with no filler. It is dense, packed into a couple of long clauses, but every clause (fields, cursor, charge policy, payment channel) carries information.

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 compensates by enumerating the return fields and the shared social schema, and it covers pagination and payment end to end. An agent can call this correctly and anticipate the cost without consulting anything else.

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%, so both parameters are already documented in the schema, establishing a baseline of 3. The description reinforces that handle accepts a bare handle or a profile URL and that cursor walks the post feed, but adds no syntax or format detail beyond the schema.

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 one public Instagram account by handle or URL) and enumerates exactly what is returned: profile fields, then recent posts and reels with their metrics, in the shared social schema. The platform name plus the field list makes it trivially distinguishable from x_profile, bluesky_profile, or linkedin_profile.

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 rather than stated: 'next_cursor pages through the full post feed' tells the agent how to paginate, and the handle/URL note tells it what input forms are accepted. There is no explicit when-to-use, when-not-to-use, or routing to an alternative (e.g. a search tool) for discovery-style queries.

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