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

With no annotations provided, the description carries the full burden. It explains the key behavioral trait: the returned JWT should be reused in other tools. It also describes side effects when client_url is provided (registering in connected apps, OpenGraph fetching, silent ignoring if already registered). However, it doesn't cover authentication failure behavior, token expiration, security considerations (e.g., sensitive nature of passwords), or whether this is a read-only or mutating operation.

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 reasonably concise across three sentences, front-loading the main purpose and then covering the optional parameter behavior. It could be slightly more structured, but it efficiently conveys the key information without 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?

Given no annotations, no output schema, and 0% schema description coverage, the description should provide more behavioral context. It covers the main purpose and the client_url side effect well, but omits important details such as error handling, token lifetime, and security expectations. For an authentication tool with no structured metadata, this is adequate but incomplete.

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 description coverage is 0%, so the description must compensate. It clarifies the purpose of client_url (the URL of the connecting app, e.g., https://claude.ai, which is registered in connected apps with name/icon via OpenGraph, and ignored if already registered). It doesn't describe username and password beyond their obvious meaning, nor does it mention any format constraints. It adds some meaning for the optional parameter but leaves required parameters implicit.

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 states a specific verb and resource in French: it authenticates a user and returns a JWT access_token for use in other MCP tools. This is distinct from the sibling mcp_register (presumably account creation) and clearly identifies this tool as the login/authentication entry point.

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 implies this tool is used to obtain credentials for subsequent tool calls by mentioning the auth_token should be reused in other MCP tools. However, it doesn't explicitly state when to use this vs mcp_register or what happens if authentication fails. The context of authentication is clear but not fully elaborated.

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