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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavioral content: that the response is the active flag plus limits plus the monthly remainder, which is important given there is no output schema. It omits auth/identity requirements for a mandate lookup, keeping it short of a 5.

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 clipped sentence, front-loaded with the audience marker "Buyer:" and with the three returned facts in a tight list. It is appropriately sized; the grammar is elliptical rather than wasteful, which is a minor readability cost rather than bloat.

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 an empty input schema, the description carries the return-value burden and does so by enumerating active status, limits and monthly remainder. Nothing critical for calling it is missing, though edge cases such as multiple mandates or currency are unaddressed.

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 baseline is 4 and there is no parameter detail the description could add or omit. The schema is empty and complete.

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 names a specific resource (card mandate) and states exactly what it reports: whether it is active, its limits, and the remaining amount this month. It implicitly separates itself from set_mandate and revoke_mandate by being a status read, but it never names those siblings explicitly.

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?

"Buyer:" establishes who should call this and in what persona context, which is real guidance. It does not, however, state when to reach for this versus revoke_mandate or set_mandate, nor any preconditions. Usage is implied rather than spelled out.

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