close_session

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

With no annotations, the description carries the behavioral disclosure burden. It explicitly discloses idempotency (closing an already-closed session is not an error) and indicates a side effect ('retire its capabilities'). It does not mention return format or pending operations, but the output schema exists to cover 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?

The description is two short sentences with no extraneous information. The purpose is front-loaded, and the idempotency note is a relevant addition that 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?

The tool is low-complexity (one parameter, no nesting) and has an output schema. The description covers core purpose and a key behavioral edge case. It could mention prerequisites or side effects more explicitly, but for this scope it is reasonably complete.

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 0%, so the description must compensate. It does not explicitly explain session_id, but the phrase 'Close a session' makes it clear that this parameter identifies the session to close. For a single, self-explanatory parameter, this is minimally sufficient but lacks explicit format or constraints.

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 uses the specific verb 'close' and identifies the resource ('a session'). It also clarifies an edge case (closing an already-closed session is not an error), which further defines the operation's scope. This clearly distinguishes it from the sibling tool open_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?

The description implies when to use the tool (when you want to close a session and retire its capabilities) and provides a behavioral usage note that closing an already-closed session is safe. However, it does not explicitly mention alternatives or exclusions, so it falls slightly short of full guidance.

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