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

Goes well beyond the annotations (readOnly/idempotent/non-destructive): deny-by-default for anything unclassified, fixed rule ordering so refusals name the most important reason, inclusive window bounds, integer minor units only, and the explicit warning that 'intent' is untrusted agent input. It also clarifies the mandate is never mutated.

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?

Front-loads purpose, then usage, then exclusions, then numeric conventions. Every sentence carries decision-relevant information; nothing is filler despite the length.

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, the description still tells the agent what comes back (verdict, rule name, report with ledger fingerprint). Combined with the nested 2-parameter schema and full annotation coverage, an agent has everything needed to call it correctly.

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%, so the baseline is 3; the description adds real semantics on top — amounts are integer minor units never floats, window bounds are inclusive, and the mandate must be treated as read-only input. It doesn't add per-field syntax beyond that, so it stops short of a 5.

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+resource+scope: check ONE proposed action against a signed agent mandate BEFORE it happens. It even specifies the return shape (verdict/rule plus a report with a ledger fingerprint) and the fixed six-rule order, so the agent knows exactly what this tool decides.

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?

Gives an explicit trigger ('immediately before any action that spends money, moves a credential or changes state on someone else's behalf') and three explicit exclusions with named alternatives: signature verification belongs to AP2, execution is not this tool, truthfulness certification belongs to attest.

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