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

The description adds meaningful behavior beyond annotations: it explains the permanent vs session-only distinction, the no-args link behavior, and the token-pasting flow for session login. It does not contradict the annotations and gives useful context about how authentication state is established.

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 compact and uses 'Best:'/'Or:' to structure the main decision. It earns its length, but the opening sentence is slightly convoluted and would be clearer if it directly stated what the tool returns.

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-parameter authentication tool, the description covers the main flows, session vs permanent setup, and how to request the login link. It does not specify the exact output shape or success/failure behavior, and it doesn't mention how 'authenticate' relates to the sibling 'connect' tool, but these are minor for this simple tool.

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 only says 'token: string' with 0% coverage, so the description carries the full burden. It does so effectively: token is the user-pasted JWT, and omitting it triggers the no-args login-link behavior. This provides exactly the semantics the model needs.

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 explains the auth flow: calling with no args returns an MCP.AI login link, and calling with the token supplies a pasted JWT for session-only login. It is specific enough about what the tool does, though it does not explicitly differentiate itself from the sibling tool 'connect'.

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?

It provides explicit usage modes: use the server config header for a permanent connection, or call the tool with the token for a session-only login, or call with no args to get the link. It misses explicit comparison with 'connect' and could more clearly separate user-configuration steps from tool-call behavior.

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