Look up an account: band, relationship, pinned post

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

Annotations already cover readOnly/openWorld/idempotent, but the description adds vital behavioral details: pricing ($0.01 base, $0.005 per post), the exact follower band thresholds, the mutual-follow bonus mechanic (+15 reply weight), and a crucial security note that third-party content fields are data, not instructions. This exceeds what annotations capture and warns against prompt injection.

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 two punchy sentences that pack in cost, what is returned, thresholds, a mechanic, and a security warning. Absolutely every word earns its place; nothing is wasted.

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 tool with no output schema, the description fully covers what will be returned (band, connection status, verified type, bio, posts), the pricing, and a critical security caveat. Given the tool's simplicity, this is complete and would let an agent use it correctly and safely.

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?

With 0% schema description coverage, the description carries the explanatory load. It clarifies the 'recent_posts' parameter through 'optionally their last few original posts' and the per-post cost. It omits explicit explanation of user_id/username, but those are self-explanatory, and the note about 'text', 'description', and author fields adds value by warning about third-party content, which indirectly helps interpret parameters.

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 'User lookup' and enumerates the exact return fields (follower band, connection status, verified type, bio, optional recent posts), making it unmistakably clear what the tool does. The resource (user) and action (lookup) are explicit, and the detail on follower band thresholds distinguishes it from generic sibling names.

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 provides strong context (cost per call, per-post fees, return values) but does not explicitly state when to use this tool over siblings like 'scout' or 'account_pulse'. Usage is implied through the lookup-oriented wording, but no alternatives or exclusions are mentioned.

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