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

Annotations only declare readOnly/non-destructive/closed-world, so the description carries the interesting behavior and does it well: online-only dependency, network egress from the station, failure whenever connectivity drops, and the warning not to place it in the sale path. One mild tension is openWorldHint=false against an 'ONLINE-ONLY' framing, but the network-egress sentence describes calls made through the documented API rather than this lookup itself, so it is not a genuine contradiction.

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 with the purpose and return shape, then the routing rule, then the constraint — a sound order. It is dense and long-ish (roughly five clauses), and a couple of parenthetical enumerations could be trimmed, but essentially every sentence carries decision-relevant content.

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, yet the description states what the lookup yields (method/path, request fields, response shape, worked fetch example), which parameters select which result granularity, the alternative tool, and the operational constraint. For a 3-param read-only lookup, nothing needed to call it correctly is missing.

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 0% and the schema gives bare string types, so the description must compensate and largely does: 'Pass resource to list a domain, operation for one endpoint, or query for fuzzy search' assigns distinct semantics to all three parameters and disambiguates resource vs operation vs query. It does not document accepted resource/operation identifiers or formats, but the three-way distinction is the key information an agent needs.

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 (look up) and resource (the Final POS REST API) and enumerates exactly what it returns: endpoint method/path, request fields, response shape, and a worked example. It also explicitly distinguishes itself from the sibling flow_lookup_command_frame and from command-frame for live POS data, so an agent can route without opening either 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?

Gives explicit when-to-use (admin/management operations command-frame cannot express: products/variants/categories, customers, outlets/stations/tax tables, webhooks), when-not (never in the sale path; command-frame is ALWAYS first choice for live POS data), and the failure mode to plan for (network egress that fails offline; degrade gracefully). This is close to a complete routing rule.

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