sensing_end_session

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

With no annotations provided, the description carries full responsibility for behavioral disclosure. It discloses the side effect (flush-on-close hook shipping buffered turns), which is valuable beyond what the input schema provides. However, it does not mention idempotency or error states, which would push it to a 5.

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 with no unnecessary words. The first sentence immediately states the purpose, and the second provides necessary behavioral detail. Every sentence earns its place.

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 no output schema and no annotations, the description explains the core action and side effects adequately. It is missing details on return values or potential errors, but for a simple end-session tool, the current description is reasonably complete. A 5 would require explicit return information.

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 description coverage is 100%, so both parameters are already described in the schema. The description adds no new semantic meaning beyond what the schema states (e.g., 'Optional brief summary' is identical). Baseline is 3, and there is no justification to raise it.

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 verb ('Signal the end') and resource ('Claude Code session') and explains the triggering of a flush-on-close hook. It distinguishes from siblings like sensing_start_session (which starts a session) and sensing_record_turn (which records turns), leaving no ambiguity about the tool's 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 implies use at session closure but provides no explicit guidance on when to use versus alternatives, such as when not to use it or prerequisites (e.g., session must be started). An agent can infer from context, but the lack of explicit statements lowers the score from a 4.

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