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

Goes well beyond the annotations (readOnly=false, destructive=false, openWorld=true) by describing the resulting state (report becomes Approved and ready for payment), the held-expense refusal rule, per-call confirmation behavior, the external-recipient warning, and the API-key access requirement.

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-loaded and dense with useful facts, but slightly overstuffed: the confirmation guidance appears twice ('By default you confirm each call' and 'confirm with the user before each call'), which is mild redundancy.

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 mutation tool with no output schema, it covers the outcome, the exception path (approve_held), the auth requirement, and the human-confirmation obligation. An agent has everything needed to invoke 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, but the description adds the consequence that motivates approve_held: a report with held expenses is refused without it. That is meaningful behavior the schema's one-line field note does not fully convey.

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 ('Approves') and resource ('a submitted report') plus the required actor relationship ('you are the approver for'). This clearly distinguishes it from sibling mutators like expensify_reject_report and expensify_submit_report.

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 explicit conditions for use: as the assigned approver, or as a Workspace Admin who may bypass the workflow. It also marks the boundary against payment ('this tool does not pay it') and the held-expense exclusion ('refused unless you pass approve_held').

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