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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds useful context about what the tool returns (leg, towns, passes, lakes with miles), but it does not explain the effect of the 'limit' parameter or how many nearby features are returned by default.

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 a single, front-loaded sentence with no wasted words. The input condition is stated first, followed by the return contents, making it easy to scan.

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 simple two-parameter lookup with annotations covering safety and no output schema, the description adequately explains what is returned. However, it omits any explanation of the 'limit' parameter, which affects the result set, leaving a meaningful gap in completeness.

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 0%, so the description must compensate. It partially clarifies the 'mile' parameter by restating its range (0 to 2656.4), but that duplicates the schema's minimum/maximum and does not explain the 'limit' parameter at all—its default of 4, maximum of 10, or what it controls (number of nearby features) are left undocumented.

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 states a specific input ('PCT trail mile') and a concrete return set ('the leg it falls in and the nearest towns, passes and lakes with their miles'), which clearly identifies the tool's operation. It does not explicitly distinguish itself from siblings like get_pct_leg or list_pct_points, so it stops short of a 5.

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?

Usage is implied by the phrase 'Given a PCT trail mile' and the return contents, but there is no explicit guidance on when to choose this tool over get_pct_leg or list_pct_points. No exclusions or alternative routing instructions are provided.

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