cards_trx_lookup

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

With no annotations provided, the description carries the full burden and does so extensively. It discloses error behavior for missing trx_id, the exact response fields, the fact that data and result are JSON-encoded strings returned without double-parsing, the semantic caveat that player is transaction attribution rather than donor provenance, the absence of BCX/donor fields, and the non-cached behavior. This is outstanding behavioral disclosure.

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 longer than average but every sentence carries useful operational information: endpoint mapping, failure mode, response shape, encoding quirk, field semantics, and caching behavior. It is front-loaded with its purpose. It could be slightly tighter by trimming the empirically-listed response fields, but given the lack of an output schema, the detail is justified.

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 tool with no annotations and no output schema, the description is remarkably complete: it covers required input, typical failure, response structure, data types, field semantics, absent fields, and caching. The main gap is the unclear semantics of the two optional parameters in the presence of a valid trx_id, and what happens for an invalid or non-existent trx_id.

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 0%, so the description must compensate. It clearly explains that trx_id must be a real trx_id and is required, and it documents that username and card_detail_id alone are insufficient. However, it does not explain what username and card_detail_id do when combined with trx_id, nor their intended roles as optional parameters. This is partial compensation, leaving meaningful gaps.

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 opens with a clear verb and resource: 'Look up the transaction object returned by GET /cards/trx_lookup for a real trx_id.' It precisely identifies the tool's operation. It does not explicitly name or contrast a sibling tool like transaction_lookup, so it stops short of full sibling differentiation, but the 'single-transaction event lookup' wording helps separate it from cached metadata endpoints.

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?

The description gives strong usage context: a real trx_id is required, and bare calls or calls with only username/card_detail_id fail with an HTTP-200 application error. It also states the route is a single-transaction event lookup and not cached as static metadata, implying when this tool is appropriate. However, it never names an alternative tool or explicitly says 'use X instead', so the when-not-to-use guidance is implied rather than explicit.

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