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

With no annotations the description carries the full burden. It does disclose two useful traits: the operation targets the authenticated user's currently active subscription, and it is financially irreversible (pas de remboursement). It omits error behavior, reversibility of access, and what occurs to the subscription record.

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?

A single sentence with zero filler, front-loading the action and resource, with the no-refund caveat parenthetically attached rather than buried.

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 destructive tool with no annotations and no output schema, the description covers the what, the whose, and the financial consequence, but leaves failure modes and post-cancellation state entirely unspecified.

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% for the single auth_token parameter. The mention of 'l'utilisateur authentifié' hints that the token binds the action to the caller's own subscription, but the description adds no token format, source, or scope semantics.

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?

States a specific verb (annule) and resource (l'abonnement Iddet Plus actif) plus scope (de l'utilisateur authentifié), which cleanly separates it from siblings like mcp_grant_subscription, mcp_get_subscription_status and mcp_list_subscriptions. An agent can pick this tool without opening any schema.

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?

Usage is only implied by the verb: cancel the active Iddet Plus subscription. There is no guidance on when this is appropriate versus checking mcp_get_subscription_status first, no prerequisites, and no statement about what happens if no active subscription exists.

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