Log in to Cursor and capture usage endpoint (fallback auth)

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses the key behaviors: opening a real browser, requiring user login, auto-discovery of endpoints, and storing the session cookie locally at ~/.cursor-usage. It could have mentioned the return/result of the tool or failure modes, but the main behavior and side effects are clearly stated.

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 three concise sentences, front-loaded with 'FALLBACK auth only.' Each sentence serves a purpose: announcing the fallback nature, specifying conditions for use, and explaining the process and outcome. No wasted words.

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?

Given the tool's interactive nature and one parameter, the description covers the rationale, conditions, and side effects well. It does not explicitly describe return values, but the absence of an output schema is balanced by the clear behavioral outcome (cookie stored, endpoints discovered). The completeness is strong, though a brief note on results would make it fully complete.

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 single parameter, timeoutSeconds, has 100% schema description coverage ('How long to wait for login + endpoint discovery. Default 240.'). The tool description itself does not elaborate on the parameter, but per the rubric, high schema coverage justifies a baseline score of 3. No additional parameter semantics are needed.

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 states the tool's purpose as a fallback login mechanism, opening a real browser to log in, auto-discovering usage endpoints, and storing the session cookie. It explicitly differentiates from get_usage by stating 'By default get_usage needs no login' and 'Use this tool only when that can't work', making the specific verb+resource+scope unambiguous.

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 guidance, listing concrete conditions such as the MCP running on a different machine, unreadable local DB, unavailable node:sqlite, or the CURSOR_USAGE_FORCE_LOGIN environment variable. It names the alternative (get_usage) and frames login as a fallback only, which is clear and actionable.

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