Spending so far

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

Annotations declare readOnlyHint=true, so the safety profile is covered; the description adds substantive value by enumerating exactly what content comes back (budget consumption, pending approvals, per-payment outcome and reasons). Remainder: no mention of how much data defaults to or error behavior.

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 sentences, front-loaded with what is returned and closing with the when-to-call cue. Slightly dense enumeration but no filler.

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?

No output schema, so the description must explain return content – and it does, itemizing the three data groups and payment outcome values. Sufficient to call confidently; a note on default result size (implied by schema) or freshness would complete it.

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?

Single optional param with 100% schema coverage (limit, default 10, max 50). The description says nothing the schema doesn't already state, so the baseline 3 holds.

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?

Specific resource and clear breakdown of the three things returned: today's spend against daily budget, pending approvals, and latest payment outcomes with reasons. Distinct from siblings pay_and_fetch (action) and spending_policy (rules) without needing to open a 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?

Gives a concrete trigger: 'Check it before a series of paid calls.' Doesn't explicitly contrast with spending_policy or say when not to call, but the pre-flight guidance is actionable and clear.

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