Close Session

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

Annotations already declare destructiveHint and idempotentHint, so the bar is lower, yet the description adds real value: it spells out the idempotent repeat-call contract (ok, already_closed=true) and the cross-request persistence trait of sessions. It does not mention permissions or error conditions beyond that.

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?

Three tight sentences, front-loaded with the action and followed by the constraints. Every clause carries information an agent needs; no padding.

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?

For a one-parameter lifecycle tool with an output schema and full annotations, the description covers the key behavioral facts (idempotency contract, session persistence). The only gap is routing relative to exec_kill, which is minor given the output schema handles return details.

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?

With a single parameter and 100% schema description coverage ('Positive id from exec_start'), the schema already carries the semantics. The description adds nothing about session_id, so the baseline 3 applies.

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?

States a concrete multi-step operation ('kill if running, join threads, free the session') on a specific resource, which is far more informative than the title alone. It does not explicitly differentiate itself from the sibling exec_kill, which appears to overlap on the 'kill' behavior.

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?

'Close every session you start' gives a clear standing directive for when to call it, and 'sessions persist across requests' explains why closure matters. It stops short of naming exec_kill or exec_list as alternatives or stating when NOT to close.

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