cad_status

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

Beyond the annotations it discloses the non-obvious traits an agent actually needs: it never installs or downloads, but under the update condition it silently runs a confined build and STL/STEP round trip costing roughly 15–20 seconds. That explains an unexpected latency burst plus the exact precondition, and the 'never installs' claim is consistent with readOnlyHint=true and destructiveHint=false.

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?

Purpose and the key negative guarantee ('never installs or downloads') are front-loaded in the first two sentences. The third sentence is dense and stacks parentheticals ('(an update)', 'about 15 to 20 seconds'), but every clause carries real information, so it stays close to efficient.

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 zero-parameter status tool with an output schema that already documents the returned readiness and version fields, the description covers everything an agent needs: what it reads, that it is side-effect-free, the slow verification path and its duration, and the exact condition under which cad_setup should be used instead.

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 tool takes zero parameters and the schema is closed with additionalProperties false, so there is no parameter meaning for the description to add. Baseline 4 applies; nothing in the description misrepresents the calling contract.

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 first sentence gives a precise verb and object: 'Read the optional code-CAD runtime's readiness and pinned version.' That scopes it to a specific runtime and to two specific outputs, so an agent can tell it is the read-only status probe for the code-CAD runtime rather than a setup/install tool.

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?

It routes the agent explicitly: when only this MCP's engine files changed and the runtime still matches the lock, call cad_status; when the runtime itself changed, use cad_setup with install: true. That is real when-to-use/when-to-use-something-else guidance, but it never distinguishes this from the other status probes (blender_mcp_status, fusion_mcp_status, bambu_network_bridge_status), so the alternative selection is only partly covered.

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