measure

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

Annotations provide readOnlyHint=false and destructiveHint=false, which indicate the tool is a read-modify operation. The description adds the return format {success, data: {mode, value, unit, segments?, id?}, message?}, which is useful. However, no additional behavioral traits like side effects on the map (e.g., temporary overlay) or authentication requirements are mentioned. The description does not contradict 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 extremely concise: two sentences. The first sentence states the purpose, and the second details the return format. No unnecessary words, front-loaded with the core action.

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?

The tool has 5 parameters, all described in the schema, and the description provides the return structure. Given the schema richness and annotations, the description is sufficient but could mention that the measurement can be displayed on the map (though the showOnMap parameter covers that). It is complete enough for an agent to use correctly.

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 all parameters are documented in the schema. The description does not add extra meaning beyond what the schema provides for each parameter; it only reinforces the overall purpose.

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 clearly states the tool's purpose: 'Measure distance or area between geographic coordinate tuples.' It uses specific verbs (measure) and resources (distance or area, coordinate tuples), and it distinguishes from sibling tools like addPolyline or addMarker which are for adding geometric objects, not measuring.

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 implies when to use the tool (when distance or area measurement is needed) but does not explicitly state when not to use it or provide alternatives. Given the sibling tools are all about adding/removing/querying entities, the usage context is clear enough.

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