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

The annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false, openWorldHint=false), so the description doesn't need to restate them. What it does add is return behavior: plain-language rules plus a fingerprint, which tells the agent that the output is human-readable and carries an identity/version value. It does not mention authorisation requirements or whether rules are account-specific beyond the phrase 'this account'.

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?

One sentence, front-loaded with the verb and resource, with the output form appended. Nothing is wasted and nothing needs to be trimmed.

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 zero-parameter read-only tool, the description covers both what it returns and the form of the return. It isn't exhaustive, because there is no output schema to lean on and the description doesn't explain the 'fingerprint' or how the rules are structured, but nothing essential for calling it correctly is missing.

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?

The tool takes zero parameters, so the schema has nothing to document; the baseline is 4. The description correctly takes no input and does not invent any.

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 uses a specific verb ('Returns') and a specific resource ('the payment rules this account is judged under'), and it names the output form ('in plain words, with their fingerprint'). It doesn't explicitly name a sibling, but the resource is distinct enough that an agent can separate it from safepay_check_payment and safepay_verify without opening the 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: the phrase 'judged under' hints at reading the rules before running a check, but the description never says when to call this tool, when not to call it, or which sibling to prefer for what purpose. The choice among the four safepay tools is left entirely to the agent.

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