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

With no annotations, the description carries the full burden. It does add genuinely non-obvious context — the call is free and sessions are auto-reaped after 30 idle minutes — but it omits what is lost by closing (cookies, page state, in-flight navigations) and what happens when the named session does not exist.

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?

Two short sentences, zero padding, with the action stated first and the idle-timeout caveat second. Nothing needs trimming.

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-optional-parameter tool with no output schema and no annotations, the description covers purpose and one behavioral trait but leaves parameter meaning and sibling disambiguation unaddressed; those are the gaps an agent would actually trip over.

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 single 'session' parameter has 0% schema description coverage and defaults to 'default', yet the description never mentions it, so the agent gets no guidance on what identifier to supply or what the default means.

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: closing the caller's browser session. However, the sibling set contains browser_session_delete, browser_session_get, browser_session_list and browser_session_put, and the description never explains how 'close' differs from 'delete' — an agent cannot disambiguate those two without guessing.

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?

No statement of when to prefer this over browser_session_delete, nor any prerequisite (e.g. that a session must be open). The only usage-adjacent information is the idle-timeout fact, which explains why closing is optional rather than required.

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