Extend Entity

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

Beyond the annotations, the description reveals the auto-selection behavior for None endpoints, the LINE+LINE support limitation, and the explicit failure condition for parallel lines. These are actionable behavioral details that help an agent predict outcomes.

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 sentences: the core operation is front-loaded, followed by the selection rule and the support/error constraints. Every sentence earns its place; no filler or redundant restatement of the tool name.

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 an output schema present and full parameter documentation, the description covers operation, parameter behavior, supported geometry, and error conditions. Nothing needed to invoke the tool correctly is missing.

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?

The schema already documents all four parameters (100% coverage), but the description adds the important semantic that None end_x/end_y means 'nearest endpoint to the boundary is auto-selected,' which clarifies what 'auto' means beyond the schema. This is real added value, though modest.

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 uses a specific verb ('Extend') with clear resources: target and boundary. It immediately distinguishes itself from sibling geometry tools like entity_trim and entity_fillet by naming the operation and the object relationship.

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 gives a clear usage context: extend a line target to a line boundary. The 'V1 supports LINE+LINE only' constraint explicitly excludes non-line inputs, and the parallel-line error tells the agent when the operation is not applicable. It does not name alternative tools, but the constraint provides enough routing guidance.

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