session_login

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

Discloses that credentials are read from environment variables (MCP_AUTH_USER_KEY or MCP_AUTH_EMAIL+PASSWORD), which is beyond annotations. No contradiction with annotations.

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, well-structured and front-loaded with the purpose. Every sentence adds value with no redundancy.

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?

While the description is clear, it does not explicitly mention the return value or outcome (e.g., session token). Given no output schema, adding that would improve completeness.

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 has no parameters, but the description explains where credentials come from (environment), providing essential semantic context, more than compensating for zero params.

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 identifies the tool as authenticating with GoCertius, specifying the verb 'Authenticate' and the resource. It distinguishes from siblings (e.g., session_info) by focusing on login/re-auth.

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 states when to use: 'call this only to force a re-login or after a 401.' Also explains that the server manages auth automatically normally, providing clear guidance on alternatives.

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