attach_session

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

The annotation 'destructiveHint: false' already indicates this is a non-destructive operation. The description adds the behavioral detail that the user must provide the session ID, but does not disclose what happens if the session doesn't exist, whether attachment changes session state, or if multiple attachments are supported. With the annotation covering the safety aspect, the description adds moderate value by clarifying the user interaction requirement.

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 two sentences long with no wasted words. It front-loads the core action and follows with clear user instructions. The only minor inefficiency is slight repetition between the two sentences regarding the session ID, but overall it is concise and 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?

Given the tool is simple (1 parameter, no output schema, no nested objects), the description covers the essential purpose and usage context. It doesn't explain return values or error conditions, but for a straightforward attachment operation with rich schema coverage, completeness is adequate for an AI agent to use it 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?

Schema coverage is 100% with only one parameter, and the schema itself includes a comprehensive description for 'sessionId' ('The Appium session ID to attach to (get from Appium Inspector or server logs)'). The tool description repeats this effectively but does not add new meaning beyond the schema, so baseline 3 is appropriate.

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 'Attach to an existing Appium session by session ID', which is a specific verb ('Attach') and resource ('existing Appium session'). It distinguishes itself from sibling tools like 'create_session' (which creates new sessions) and 'delete_session' (which terminates sessions), making the purpose unambiguous.

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 explicitly instructs the agent to 'Ask the user to provide the session ID' and explains where to find it ('visible in Appium Inspector or in the Appium server logs next to the session creation event'). This provides clear guidance on when to use this tool - only when a session already exists and the user can supply its ID, distinguishing it from 'create_session' which does not require an existing session.

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