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

With no annotations, the description carries the burden and does well: it discloses the extension dependency, that HttpOnly cookies are included, that an interactive operator approval gate exists, and that returned values are sensitive. It omits what happens if the operator denies the prompt and whether values come back raw or redacted.

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 compact sentences, front-loaded with the purpose before mechanism, precondition, and safety caution. Dense and largely waste-free, though the 'via BrowserGPT extension: chrome.cookies' fragment packs three ideas into one clause and slightly blurs the read target.

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 7-parameter tool with no annotations and no output schema, the description covers the permission workflow and sensitivity but says nothing about the return shape (does it return cookie values, names, domains, expiration?) or error behavior on denial. Adequate to invoke, insufficient to predict the result.

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 description coverage is 100% and the schema already explains tab_id, cookie_domains (with a domain-format example), key filters, and confirmation_message. The description only restates which sources are optional, adding little semantics beyond the structured fields, 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 specific verb ('Read') and resource ('session data for a tab') and enumerates the concrete sources: chrome.cookies including HttpOnly, plus optional localStorage/sessionStorage keys. No sibling tool in the list reads cookies or session storage, so the agent can distinguish it without opening the schema.

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?

Gives a clear usage context ('session export / porting auth') and an explicit prohibition ('do not paste values into chat'), plus the precondition that the operator must approve the in-tab permission prompt. It does not name an alternative tool or say when not to use it (e.g. prefer browser_exec_js for page-scoped reads), so it stops short of 5.

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