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

Annotations already cover readOnly, idempotent and non-destructive, so the safety profile is established. The description adds useful context beyond that: it enumerates what is compared (entry price, plans, cost traps, price rules, research status, pricing date) and notes that no purchase/cancel/switch action occurs, reinforcing the read-only contract.

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?

Three tightly packed sentences: what it does, what to pass, what it reports, and the side-effect disclaimer. Front-loaded with the action and the input convention, with zero 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 exists, so the description must sketch the return value, and it does by naming the fact categories and the affected conclusions. This is sufficient for an agent to invoke and interpret the tool, though a note on whether the entire dossier must be byte-identical (for idempotency reasoning) would close the last gap.

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?

With 0% schema coverage on a nested, open-ended object parameter, the description carries the burden and does so with 'pass the whole dossier back' — clarifying this is a full round-trip of the previously returned object rather than an ID or partial patch. The internal structure of the dossier remains undocumented, but it is implicitly the output of the build step.

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 and resource ('Re-check a purchase file') and ties itself to the sibling workflow by referencing a dossier 'built earlier'. An agent can immediately distinguish this from build_purchase_dossier or the generic check_* tools.

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?

Implies the precondition clearly: use this when you already hold a dossier from a prior build and want to know what changed. It does not explicitly name build_purchase_dossier as the counterpart or state when not to use it, but the context is unambiguous.

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