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

Annotations already declare readOnly, idempotent, and non-destructive, and the description aligns with that by saying 'Read-only: it places no order.' On top of that, it discloses subtle behaviors: quoted_at is not a price hold, place_order re-prices from the same data, reasons state only positive attributes so absence is never a drawback, and tradeoffs uses null when one side lists nothing.

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 description is long, but the tool is complex and has no output schema, so the density is justified. It front-loads the core output and then groups caveats and usage rules coherently, though a couple of clauses could be tightened without losing information.

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?

There is no output schema, so the description must carry return-value meaning, and it does: it enumerates returned fields, rejection reasons, quoted_at, catalog_version, tradeoffs deltas, and the sensitive flag. Given the seven parameters and five sibling tools, an agent has everything needed to invoke it correctly and interpret the result.

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 100%, so the baseline is 3, but the description adds meaningful cross-parameter semantics: service_id can be replaced by platform+goal, quantity must be accepted by every pick, and priority is defined in terms of LISTED delivery rate then start window with a fallback to balanced. This goes beyond the schema's per-parameter descriptions.

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+resource ('Recommend which plan option to order') and details the output: one recommendation plus the cheapest, highest-quality and fastest-listed alternatives. It clearly differentiates from get_service by saying 'Prefer this over reasoning across every option from get_service' and by specifying the option_id hand-off to get_quote and place_order.

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 tells the agent exactly when to use this tool: to choose and explain a choice, and to avoid reasoning over every option from get_service. It also gives identification alternatives (service_id OR platform + goal), the follow-up workflow (re-call and compare catalog_version before ordering), and explicit prohibitions such as never presenting a pick as a percentage more expensive than another.

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