Measure Area

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

Beyond the readOnly and idempotent annotations, the description discloses that the tool measures the numbers in the call, not the drawing, and that results are exact only for straight-edged polygons. It also warns about under-reporting on curved edges when bulge is omitted and references an 'assumes' field, adding meaningful behavioral context.

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?

Three tight paragraphs with no filler. The main purpose is front-loaded, and every sentence adds either capability, usage routing, accuracy caveats, or schema-related context. The formatting makes the key warnings 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 single-parameter tool with a detailed input schema, an output schema, and safe read-only annotations, this description is complete. It covers what the tool does, when to use the alternative, how curved edges affect accuracy, and what assumptions the output reports.

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?

Although the schema already documents the points array well, the description adds important semantic nuance: it clarifies the tool operates on literal coordinates rather than drawing entities, explains the bulge element's role in arc edges, and quantifies the accuracy penalty of omitting it. This goes well beyond the baseline schema coverage.

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 verb and resource: it computes the area and perimeter of a polygon from supplied vertices. It also clearly differentiates itself from the sibling analysis_measure_entity, which measures real drawing geometry.

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 explicitly says when to use this tool versus the alternative: use it only when you have literal coordinate vertices, and use analysis_measure_entity(handle) to measure something that already exists in the drawing. This gives an agent unambiguous routing guidance.

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