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

With no annotations, the description carries the full burden and discloses non-obvious behavior: amounts and tax are manually typed by the worker, core never reads or fills them in, spent_on defaults to today in the shop time zone, and possible PO duplicates are listed for confirmation. It does not cover permissions, error cases, or the exact response shape, which keeps it from 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?

The purpose is front-loaded and each sentence adds information: the PO duplicate caveat, manual amount entry, and date default all earn their place. The PO duplicate sentence is slightly dense but not wasteful.

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 an unannotated mutation tool with no output schema, the description covers the main workflow and duplicate warning but omits return values, permission requirements, and error behavior. It is adequate but not complete enough to remove all ambiguity for the agent.

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 description coverage is only 25%, so the description needs to compensate. It adds useful meaning for amount_minor, tax_minor, spent_on, and receipt_media_id, but leaves job_id, vendor, category, and note unexplained beyond their schema types.

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 states a specific verb and resource: recording money a worker spent on a job, including the receipt photo. It also clarifies the boundary with purchase-order costs, so an agent can distinguish this expense entry from PO receiving or general job costing.

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 a clear usage caveat: parts received on a PO are already job cost, and matching vendor receipts are surfaced via possible_po_duplicates so the agent should ask before keeping both. It does not explicitly route to sibling tools like expenses_update or materials_add, but the main when-to-check guidance is present.

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