end_session

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions recording a 'session_ended' event, but does not describe side effects such as whether the session becomes read-only, if pending operations are cancelled, or any authentication/authorization requirements. For a lifecycle tool, this is a significant gap.

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 (27 words in the main sentence) and front-loaded with the essential purpose. It includes a return format section, which is helpful. There is no wasted content. However, it could be more structured by including parameter guidance in a compact form.

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 4 parameters, no annotations, and an output schema. The description explains the return values but not the parameters. For a tool that ends a session, it should inform the agent about the importance of providing a meaningful summary and the correct session_id. The sibling tools suggest a decision/evidence context, but the description does not integrate this. Overall, the description is incomplete for correct usage.

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 4 parameters with 0% description coverage, meaning the schema provides no documentation. The description does not compensate by explaining any parameter's purpose, format, or constraints. For example, 'summary' and 'session_id' are critical for correct invocation but are left undefined. The only hint is 'agent_name' defaulting to 'claude_code', but this is not mentioned in the description.

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 tool is for ending a work session, with the verb 'close' and the context 'at the END of a work session'. It distinguishes from sibling 'start_session' by being the complementary action. The mention of recording a 'session_ended' event further clarifies its role.

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 says to call at the end of a work session, providing clear usage timing. It also explains the benefit ('so the next agent can see what was done'). However, it does not explicitly state when not to use it or mention alternatives, but the context is sufficient for most cases.

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