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

Annotations cover safety (idempotentHint: true, destructiveHint: false), and the description adds meaningful side-effect context: it can trigger a browser login flow, accept a JWT for session-scoped state, or return a link. The non-obvious session-vs-permanent distinction is well disclosed, and the text does not contradict the idempotent hint since repeated auth calls are benign. No annotation contradiction detected.

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 information-dense sentences cover the essential content without wasted words. The 'best' vs. 'or' structure effectively separates the preferred permanent setup from the session fallback, though the first sentence runs on slightly and could benefit from a colon or semicolon. Overall, every phrase earns its place.

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-optional-param authentication tool with no output schema, the description covers the critical aspects: the three invocation paths and their side effects on auth state. It effectively works around the absence of schema field descriptions. Minor gaps exist—such as no explicit statement of what the no-args call returns beyond 'get the link'—but these are largely inferable from the text.

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 coverage is 0%, so the description carries the full burden of documenting the sole 'token' parameter. The description explicitly instructs 'call with { token: "<jwt>" } after the user pastes', which adds the format and usage context absent from the schema. While this compensates well for the missing schema documentation, some ambiguity remains about whether the token expects a raw JWT or other auth payloads, despite the JWT hint.

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?

'authenticate' clearly states the verb and resource: authenticating to MCP.AI. The description goes further to distinguish three invocation modes (permanent config, session token, link retrieval), each with distinct outcomes. This is a specific, unambiguous purpose that doesn't rely on the tool name alone.

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 provides explicit when-to-use scenarios: permanent config header for long-lived access, pasted token for session-only, and no-args to retrieve a login link. This effectively guides the agent on the appropriate invocation based on need, though it doesn't contrast these options against sibling tools like 'connect'.

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