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

Annotations already declare readOnlyHint=false and idempotentHint=true; the description corroborates idempotency ('already closed is harmless') and adds non-annotation context that the browser resource is released. It does not describe error behavior for an invalid or foreign sessionId.

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 short sentences with the action front-loaded, then the parameter, then the edge case. Every sentence earns its place and nothing is padded.

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 single-parameter, non-destructive, idempotent teardown with annotations covering the safety profile, the description supplies what an agent needs to invoke it. Missing only failure-mode detail (invalid/foreign sessionId), which is a minor gap.

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 and schema description coverage is 100%, with the schema already stating it is the `sessionId` `session_call` returned. The description's 'Pass the `sessionId`' therefore adds no meaning beyond structured data; 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 specific verb and resource ('Ends a session') and ties it directly to the sibling that creates it, `session_call`, so an agent can distinguish close from call without opening either schema. The added 'frees its browser' clarifies the resource impact.

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?

Implicitly scopes usage to sessions created by `session_call` and explicitly reassures that re-closing is harmless, which is the main when-to-call ambiguity. It gives no explicit negative guidance (e.g., what happens if the sessionId is unknown or from another user), so not a full 5.

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