Get a profile

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is covered. The description adds genuinely new behavioral facts the annotations cannot express: cost of 1 credit per call, failures are free, and cached repeats are free when using max_age_days. That pricing/caching disclosure is exactly the kind of context an agent needs before spending credits.

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 sentences, front-loaded with the core action and return fields, then scope, then cost, then routing. The one inefficiency is the full re-listing of 17 platforms, which duplicates the enum already present in the schema — it costs length without adding 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?

For a 4-parameter, read-only, single-resource lookup with 100% schema coverage and full annotation coverage, the description supplies the remaining essentials: what fields come back, platform breadth, credit cost, and cache/failure economics. With no output schema, the inline field listing compensates adequately.

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 the schema already explains url, handle, params, and platform, and the platform enum is fully enumerated. The description restates the handle-or-URL choice and re-lists platforms, adding no new semantics — notably it says nothing about the open-ended `params` object beyond what the schema's 'call describe' hint provides. Baseline 3 applies.

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 opens with a specific verb and resource ('Get a profile') and enumerates the returned fields (name, bio, follower counts, links), so the agent knows exactly what comes back. It also names the input modes (handle or URL) and the platform scope. The only softness is the vague boundary phrase 'anything beyond this', which leaves the split with platform-specific tools slightly fuzzy.

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 an explicit alternative rule: 'For anything beyond this, use the platform's own tool', which routes the agent away from this tool for richer per-platform needs. However, 'anything beyond this' is undefined — it never says what counts as beyond (posts? comments? analytics?), so the agent must guess. No prerequisites or exclusions beyond that one clause.

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