Close session

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

Annotations already mark the tool as mutating (readOnlyHint: false) and open-world (openWorldHint: true). The description adds 'frees its resources', which gives a concrete outcome beyond the annotations. However, it does not disclose that the session becomes unusable after closing, that state is destroyed, or that the operation is irreversible, which would be valuable behavioral detail given the mutation hint.

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 a single, complete sentence with no redundant words. It front-loads the primary action and adds a meaningful effect, achieving maximum clarity in minimal space.

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 tool with one parameter, no output schema, and simple semantics, the description is adequate. It states the purpose and the resource freed, which is enough for an agent to know when to call it. It could mention that the session is no longer valid afterward, but that is largely implied by 'closes'. Given the low complexity, completeness is high.

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 already documents sessionId with a clear source ('Session id returned by browser_start'), achieving 100% coverage. The description adds no further detail about the parameter, so it relies entirely on the schema. Baseline of 3 applies because the schema carries the burden effectively.

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 action ('Closes'), the resource ('a browser session'), and adds a behavioral effect ('frees its resources'). It is specific enough to distinguish from siblings like browser_start (which creates) and browser_navigate (which moves). No ambiguity in intent.

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 usage in a lifecycle context: it is the counterpart to browser_start, but it never explicitly says 'use after you are done with a session' or mentions alternatives. For such a simple tool, the absence of explicit guidance is acceptable, but it stops short of giving a clear when-not or discussing cleanup ordering.

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