Fusion360 MCP Server

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

Annotations indicate this is a non-readOnly, non-idempotent, non-destructive operation, which the description aligns with by implying mutation ('extend') without contradiction. However, it adds minimal behavioral context beyond annotations—no details on error conditions, rate limits, or what happens if no intersection exists—leaving gaps in understanding the tool's full behavior.

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 highly concise and front-loaded, using two clear sentences with zero wasted words. Every phrase ('extend a sketch curve', 'to the nearest intersection', 'The end nearest to the given point') directly contributes to understanding the tool's function efficiently.

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?

Given the tool's moderate complexity (mutation without annotations covering all behaviors) and lack of output schema, the description is adequate but incomplete. It explains the core operation but omits details like return values, error handling, or interaction with other sketch tools, leaving the agent to infer some aspects from context.

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?

With 75% schema description coverage, the schema documents three parameters well, but 'sketch_name' lacks a description. The description adds value by explaining the purpose of 'point_x' and 'point_y' ('near the end to extend') and implying 'curve_index' selects the target, though it doesn't fully compensate for the missing 'sketch_name' documentation, keeping it from a perfect score.

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 specific action ('extend'), target resource ('a sketch curve'), and precise behavior ('to the nearest intersection') with the end selection logic ('The end nearest to the given point is extended'). It distinguishes from siblings like 'trim_curve' or 'offset_curve' by focusing on extension rather than cutting or offsetting.

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 provides no guidance on when to use this tool versus alternatives like 'trim_curve' or 'offset_curve', nor does it mention prerequisites such as needing an existing sketch or intersecting geometry. It lacks explicit context for tool selection among the many sibling CAD operations.

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