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

Annotations already signal read-only, non-destructive behavior, so the description's burden is lower. It adds useful behavioral detail beyond annotations: for platform+username inputs it 'resolves through the profile endpoint and returns the profile record plus the underlying creator record,' and for UUID inputs it explains how `include: ['profiles']` changes the response. It does not discuss edge cases like invalid/missing identifier combinations, but the main response-shaping behavior is transparent.

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 front-loaded with the core purpose, followed by explicit when-to-use bullets, then parameter behavior, then examples. Every sentence serves a distinct purpose and the examples are compact and illustrative rather than redundant. Despite covering two input modes and several sibling tools, the structure keeps the content scannable.

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?

Given the output schema and annotations, the description is complete for an agent to select and call the tool correctly. It covers both identifier modes, the optional include behavior, example invocations, and clear routing to relevant siblings. No critical operational context—such as whether this is read-only, destructive, or how to format inputs—is missing.

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 the baseline is 3, but the description adds significant meaning beyond the schema. It explains the mutually exclusive lookup modes: `id` alone versus `platform`+`username`, and clarifies that `include: ['profiles']` only matters in the UUID path because the platform+username path already returns matched profile context. The examples additionally map user phrasing to concrete parameter values.

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: 'Fetch the full record for a single creator by ID or exact platform username.' It clearly distinguishes this tool from siblings by naming `get_profile` for profile-specific needs and `lookup_profiles` for batch exact lookups. The two supported lookup modes are explicit and each is tied to prior tools like `search_creators` and `semantic_search_creators`.

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 says 'Use this when you already have either' and enumerates the two exact conditions. It also gives explicit exclusions and alternatives: use `get_profile` if profile metrics are the main need, and use `lookup_profiles` for batch exact profile lookups. Examples map natural user requests to the correct parameter combinations.

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