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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered; the description adds value beyond that by naming the auth requirement ('Needs the organisation's key') and by disclosing that pending approvals may already carry a prepared transaction. It stops short of describing volume, ordering, or pagination behavior for the audit trail.

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?

Purpose and scope are front-loaded in the first sentence, and the three short trailing sentences each add a distinct fact (single-approval mode, read-only, auth requirement). It is dense but nearly every clause earns its place; only the trailing 'Read-only' mildly duplicates the readOnlyHint annotation.

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 carries the burden of explaining return content, and it does so by naming all three returned collections. It is complete enough to call correctly, with only minor gaps around result volume and ordering.

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 rapr_ prefix and its origin (prepare_payment) are already documented, making 3 the baseline. The description goes slightly beyond by stating the behavioral effect of supplying approval_id — the response narrows to that single approval — which the schema does not express.

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 opens with a specific verb ('Read the controls that govern the payments an agent prepares for an organisation') and then enumerates the three concrete resources returned: spend profiles with today's/monthly spend against each budget, payments awaiting human approval, and the audit trail. This is materially different from siblings such as approval_status or request_payment_approval, and an agent can pick this tool 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?

It gives clear usage context — this is the read path for governance data, with a stated mode switch ('With approval_id, reads that one approval'). What it lacks is explicit routing against close siblings like approval_status or request_payment_approval, so the agent must infer which read tool to prefer.

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