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

Annotations already declare destructiveHint=true and idempotentHint=true, but the description adds meaningful consequence detail: canceling spends no money and permanently prevents future merchant charges. This clarifies the real-world effect beyond the flags, though it never states what happens on a repeat call or an already-cancelled mandate.

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 short sentences, action first, effect second. No filler and nothing repeated from the annotation block.

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 mutation tool with annotations covering safety and idempotency, the description conveys action, permanence, and no-spend behavior. The remaining gap is where mandate_id comes from, which is not explained anywhere given the empty schema descriptions.

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 coverage is 0% for the single mandate_id parameter, and the description only implies that it identifies a subscription mandate. It gives no format, source, or lookup hint, so it fails to compensate for the schema gap, though the parameter's purpose is at least inferable.

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 and resource ('Cancel a subscription mandate'), which is clearly distinct from siblings like request_subscription, list_subscriptions, and request_payment. It does not explicitly name an alternative tool, but the action and target are 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?

No guidance on when to use this versus list_subscriptions (to find the mandate) or how to obtain a mandate_id. There are no stated prerequisites or exclusions, leaving the agent to infer the workflow.

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