close_session

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

Description discloses side effects (freeing resources) and error cases (idle-expired, evicted, crashed). No annotations, so description carries full burden; it's sufficiently transparent.

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?

Two concise sentences, no wasted words. First covers action and return, second adds usage guidance and error behavior. Front-loaded with key action.

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?

Simple tool with one parameter and no output schema. Description adequately covers purpose, return, resource freeing, and error handling. Implicit prerequisites are acceptable.

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?

Only one parameter with schema description 'Session ID to close'. Tool description doesn't add meaning beyond schema; baseline 3 due to 100% coverage.

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?

Clear verb 'close' with specific resource 'browser session'. Mentions freeing resources and return value. Distinguishes from sibling tools by specifying it's for finishing a 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?

Explicitly states 'Call it when finished' and describes error behavior for closed/expired IDs. Provides good context on when to use, though lacks explicit exclusions.

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