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

Annotations already indicate idempotent=true, readOnly=false, and destructive=false. The description adds valuable behavioral details: the permanent non-expiring nature of the header-based auth, the session-only scope of pasted tokens, and the fact that calling with no args returns a login link. It does not contradict any annotations, though it does not describe potential side effects or exact return values for successful token submission.

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 front-loaded with purpose and uses three sentences to cover all invocation modes and configuration options. Every sentence contributes useful information, though there is slight redundancy in 'log in in the browser, copy the access token' and 'paste it here' phrasing, but it remains concise overall.

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 one-parameter authentication tool with no output schema, the description is quite complete: it explains the browser flow, permanent vs. session-only options, and how to invoke with or without a token. The main gap is that it does not specify what a successful token-based call returns (e.g., confirmation message), but the core usage is well covered.

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 schema only defines 'token' as a string with zero description coverage, so the description carries the full burden. It compensates exceptionally well by explaining the token is a JWT copied from the browser, how to use it in the call, and that omitting it returns a login link. This gives far more semantic meaning than the bare schema.

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 explicitly states the tool's purpose: logging into MCP.AI by obtaining an access token from a browser. It clearly describes the resource (MCP.AI) and the action (log in, get link, send token), and the invocation modes (no args, with token, config header) make the behavior unambiguous. It is differentiated from sibling tools by its focus on authentication flow rather than generic connection or utilities.

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 gives clear usage context: it recommends adding the token as an Authorization header for a permanent connection, or pasting it for a session-only login. It also instructs the agent to call with a token after the user pastes, or with no arguments to get the link. However, it does not explicitly mention when not to use this tool or name alternatives from the sibling list, such as 'connect'.

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