list_rigs

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

Annotations already declare readOnlyHint: true and openWorldHint: true. The description reinforces this with 'Read-only — does not start a session.' It also adds context about the USABLE flag meaning and the required user actions for non-usable rigs. No contradictions with annotations.

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 concise: four sentences, each essential. The first sentence states the purpose and output. The second emphasizes read-only nature. The third provides ordering instruction. The fourth explains USABLE and failure response. No filler, well-structured.

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?

The tool has zero parameters and no output schema. The description fully compensates by listing the output fields, explaining the USABLE condition, and providing error-handling guidance. It covers all necessary context for an agent to use this tool correctly.

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 input schema has zero parameters (schema_description_coverage 100%). With no parameters, the baseline is 4. The description adds value by explaining the output fields and their meaning (id, name, online, etc.), which is not in the schema.

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 explicitly states the verb 'List', the resource 'Windows machines (rigs)', and the scope 'paired to this API key'. It lists the returned fields (id, name, online, api_access_enabled, USABLE). This clearly distinguishes it from sibling tools like start_session and end_session.

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 explicit usage guidance: 'Call first before start_session.' It explains the USABLE condition (online AND api_access_enabled) and tells the agent what to do if none are USABLE (instruct user to install agent, pair, and enable access). No alternative tools are mentioned, but the guidance is complete for this tool's context.

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