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

With no annotations, the description carries the full burden and does so: it discloses the downstream effects on charging and auto top-up, the no-op return shape, a per-call credit cost that is charged even on rejection, the 429 exception, and request_id in errors. That is materially more than 'delete' would imply.

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?

Four sentences, front-loaded with the action and its effect, then return value, cost, and error handling in order of decision relevance. Every sentence carries operational information; nothing is repeated from the schema.

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 destructive single-entity call with no annotations and no output schema, the description supplies the missing pieces: side effects, cost model, rate-limit exception, and error contract. An agent can call it and interpret the result without further documentation.

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 100% and each parameter is documented inline, including the x402 payment payload, so the baseline is 3. The description adds no parameter-level detail beyond the schema.

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 ('Remove a user's saved card') and adds the mechanism ('detached in Stripe'), which distinguishes it from siblings like get_saved_payment_method and delete_auto_topup. No need to open the schema to know what it does.

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 context is conveyed through consequences: charge_saved_card and auto top-up stop working until a new card is saved, and the no-op case returns deleted: false. There's no explicit 'use X instead' routing to a sibling, but the blast radius is clear enough to decide when to call it.

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