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

Annotations already declare read-only and idempotent hints, but the description adds valuable behavioral context: it requires the profile to be 'tracked', it costs 1 credit per call, and it clarifies that the averages serve as the baseline for outlier scores. This goes beyond the annotations without contradicting them.

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 three sentences: purpose, content details, and workflow/cost. Every sentence is useful and front-loaded, with no filler or repetition.

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 single-profile fetch, the description covers what data is returned (followers, bio, averages, recent posts), explains the meaning of averages, and includes cost and the prerequisite search step. It lacks details on time window definitions and post count limits, but these are minor for a fetch operation with no output schema.

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 descriptions cover platform and profileId clearly, and the description reinforces that profileId comes from search results. However, the handle parameter has no schema description and the tool description doesn't clarify its semantics beyond the workflow note. With 67% schema coverage, the description partially compensates but not fully.

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 'Fetch one tracked profile by id', which is a specific verb+resource that clearly states the tool's function. It distinguishes itself from siblings like list_tracked_profiles by focusing on a single profile and from search_profiles by being the post-search retrieval step, reinforced by the direct instruction to use search_profiles first.

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 gives an explicit workflow ('Use search_profiles first to resolve a handle to an id') and mentions the cost per call, which helps decide when to invoke it. However, it does not explicitly contrast with alternative tools like list_tracked_profiles for bulk operations or note when not to use this tool.

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