Fusion360 MCP Server

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

Annotations indicate non-read-only, non-idempotent, and non-destructive operations, but the description adds valuable context: it specifies that the tool runs arbitrary Python (implying potential side effects), returns the last expression's value (REPL-style), and lists pre-defined names (app, ui, design, etc.). This clarifies execution behavior beyond annotations, though it doesn't detail error handling or security constraints.

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 front-loaded with the core purpose, followed by essential behavioral details in a single, efficient sentence. Every part adds value without redundancy, making it appropriately sized for the tool's complexity.

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 high complexity (arbitrary code execution), lack of output schema, and minimal annotations, the description is reasonably complete. It covers purpose, behavior, and parameter context, but could improve by mentioning error cases, execution limits, or safety warnings to fully guide an AI agent.

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 0% schema description coverage for the single parameter 'code', the description compensates by implicitly defining it as Python code to execute. It adds meaning by mentioning REPL-style return and pre-defined names, which help interpret the parameter's expected content. However, it doesn't specify syntax examples or constraints.

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 ('Run arbitrary Python in Fusion 360') and resource (Fusion 360 environment). It distinguishes itself from all sibling tools by being the only code execution tool, with siblings focused on CAD operations like modeling, constraints, and measurements.

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 usage for executing Python code within Fusion 360, particularly mentioning REPL-style behavior and pre-defined names. However, it doesn't explicitly state when to use this versus other tools (e.g., for automation vs. direct CAD operations) or provide exclusions, leaving some ambiguity.

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