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

Annotations declare idempotentHint=true but not readOnlyHint, which implies mutation. The description adds that it triggers a browser login flow ('log in in the browser') and returns a link when called with no args, and that token login is 'session-only' vs 'permanent' via config. It does not state what the response looks like (link or success message), but the annotation set is minimal and the description covers the key behavioral contexts (login process, persistence).

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 sentences, but packed with essential guidance. The first sentence establishes purpose and audience. The second sentence explains the two usage modes with explicit call syntax. Slightly dense but no fluff; could be split into bullets, but it's efficient for an auth tool that needs to convey both browser flow and API usage.

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 simple login tool with 1 optional param, the description covers the core flow: browser login, token capture, config vs session options, and empty-call behavior. Missing details: what the response contains when returning the link, timeout behavior, or error handling, but given the low complexity and no output schema, this is adequate for an agent to initiate authentication. The 'permanent, non-expiring' note is a helpful extra.

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 has 1 optional parameter 'token' with 0% description coverage. The description explains the token's meaning ('<jwt>' pasted from browser) and its role in session vs permanent login. It explicitly says 'or with no args to get the link', which clarifies the optional nature. This adds meaning beyond the bare schema, though it doesn't detail token format beyond '<jwt>'.

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?

Purpose is clearly stated as 'log in' for MCP.AI, but the description actually says the tool's purpose is 'MCP.AI for IDE agents (Cursor, etc.). The description states it 'authenticate' is a clear verb+resource ('authenticate' with a 'for IDE agents' audience qualifier, plus 'token' parameter and 'no args to get the link'). The target audience 'IDE agents (Cursor, etc.)' distinguishes it from sibling tools like 'connect' or 'marketplace' which imply different resources.

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?

Explicitly provides two usage paths: 'add it to this server's config as a header... for a permanent, non-expiring connection' vs 'paste it here for a session-only login'. States the exact call patterns: 'call with { token: "<jwt>" }' or 'with no args to get the link'. Sibling tools are not mentioned, but the tool's role in the auth flow is clearly differentiated by the config vs session distinction.

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