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

No annotations are provided, so the description must fully disclose behavioral traits. It only states 'Returns mean and detail' without mentioning safety (read-only), rate limits, authentication needs, or any side effects. This is minimal disclosure for a tool with no annotations.

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 short (two sentences) and uses bullet-like structure, but it includes inaccurate information (mode parameter) and vague phrasing ('Returns mean and detail'). It could be more precise and accurate without extra length.

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 tool supports four types of averages, the description does not explain the differences or when to use each. An output schema exists, so return details are partially covered, but the missing 'mode' parameter and lack of behavioral context leave the description incomplete.

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 100% schema coverage, the baseline is 3, but the description introduces a nonexistent 'mode' parameter, misrepresenting the actual schema. It adds little beyond the schema's 'Array of numbers' and 'Optional weights for weighted average', and the inaccuracy reduces the value.

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?

Description states 'Compute simple, weighted, geometric, or harmonic mean' which clearly identifies the tool's purpose. However, it mentions a 'mode' parameter that does not exist in the input schema, causing confusion. It does not explicitly differentiate from the many sibling calculate_ tools, only referring to a bundle for related calculators.

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 suggests use cases like 'grade averages, returns, or rates' and points to list_bundles for related calculators. It lacks explicit guidance on when not to use this tool or comparisons to specific siblings, leaving the agent to infer from the large sibling list.

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