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

With no annotations, the description carries the full burden and does disclose genuinely non-obvious behavior: the call initiates a purchase that returns a payment challenge rather than completing payment, and settlement requires an external authorized client. It still omits what happens to the challenge, whether retries are safe, and any permission/rate-limit constraints.

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 with the core action and the payment caveat front-loaded; every clause carries information. The 'generic clients' phrasing is slightly opaque but not wasteful.

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 two-parameter mutation with no annotations, no output schema, and an entirely undocumented free-form body, the description leaves real gaps: how to construct the body and what a challenged response means for next steps. It covers the high-level flow but not enough to call the tool confidently.

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% and 'body' is an unconstrained nested object, so the description must compensate. 'Its exact business body' hints that the object must be complete (matching additionalProperties: false) but never explains what fields belong in body, how to obtain them from foundry_products, or what product_id refers to beyond the name.

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 gives a concrete verb and resource ('Buy a configured public product') and names both required inputs, which is enough to distinguish it from the read-only siblings. It doesn't explicitly contrast with foundry_purchase_read, so an agent must infer the difference from the name alone.

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?

'Generic clients receive a payment challenge; paying requires an external authorized client' implies that this tool alone cannot complete a purchase for an ordinary caller, which is useful routing information. However, it never states the alternative path (e.g. use foundry_purchase_read or delegate to an authorized client) or the prerequisite for calling it successfully.

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