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

No annotations are provided, so the description carries the full burden. It usefully discloses cost ('Free') and a privacy constraint ('No personal information'), which are real behavioral facts, but it says nothing about whether a durable request record is created, what confirmation the caller gets, or any rate limits.

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 short clauses, front-loaded with the key fact ('Free.') and then the action, examples, purpose, and constraint. Nothing is padded.

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?

With no output schema and no annotations, the description covers the essentials: what to submit, that it's free, and the privacy boundary. It omits what happens after submission (acknowledgement, follow-up), which is a minor gap for a lightweight feedback tool.

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 100%, so all five parameters are already documented in the schema. The description only echoes one of them ('the most you'd pay per read' -> maxPricePerReadUsd) and adds no syntax or format detail, so baseline 3 applies.

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 action (tell Subpay about a document or field it can't yet read) and the resource it targets, and explicitly frames it as a gap relative to the sibling extract_document. An agent can tell this apart from extract_document and about 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?

The condition that selects this tool is explicit: use it for a document/field extract_document doesn't support yet, and it explains the downstream purpose ('used to decide what to build next'). It stops short of an explicit when-not statement, but the routing against the sibling is clear.

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