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

Annotations already declare readOnly/openWorld safety, but the description adds real value by disclosing the computation method (Vincenty ellipsoidal) and the rich result set: km/miles/nautical miles, bearing, compass, midpoint, flight time, and distance matrices. This tells the agent what it gets back beyond the safety profile.

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 first two sentences redundantly restate the title/name ('Distance between two places or coordinates. Distance between two places.'), wasting prime front-loaded space. The later sentences do carry useful content, but the definition is padded.

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?

With no output schema, the description responsibly enumerates the return fields and input formats, which is what an agent needs to call and interpret the tool. It stops short of any usage routing against sibling tools, which is the main remaining gap.

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% and both parameters are documented with examples (coordinates, city, airport code). The description restates the accepted formats but adds no syntax or constraint detail beyond what the schema already provides, so 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 names a specific computation (distance) between two named inputs and enumerates accepted input formats. However, it never distinguishes itself from the close sibling airport_distance, so an agent cannot tell which one to pick without opening both.

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 no when-to-use or when-not-to-use guidance and no alternative tool is named, despite airport_distance being an obvious overlapping sibling. The only implied guidance is the general capability itself.

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