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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the description's claim of being 'Read-only' is consistent. However, it adds only the data source detail ('Explorer PGRO tx_receipts') without further behavioral context like response shape or performance characteristics.

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?

A single, well-structured sentence that front-loads the primary action ('Read-only usage statistics') and concisely specifies the data source and filter types. No extraneous 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?

Given the output schema exists (presumably defining the returned statistics) and annotations cover safety and idempotency, the description provides sufficient context on what the tool does and its data provenance. However, a brief note on the difference between the two filter types (rules vs. OSTC/process) could further aid understanding.

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 100%, so baseline is 3. The description adds value by explaining the 'type' parameter's options ('xrc137' or 'xrc729') correspond to the two filter concepts, which provides context beyond the schema's generic 'Operation or handoff type identifier.' Other parameters like 'ostcId' and 'windowHours' lack elaboration, but the key filter dimension is clarified.

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 clearly states the tool provides 'Read-only usage statistics' from a specific data source ('Explorer PGRO tx_receipts') and mentions the two filtering dimensions ('XRC-137 rules or XRC-729 OSTC/process filters'), which distinguishes it from sibling tools that focus on specific session data or transaction logs.

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 implies usage for retrieving aggregate usage statistics but does not explicitly indicate when to use this tool over alternatives like 'get_xdala_session_timeseries' or 'get_xrc_failure_stats'. No when-not or alternative scenarios are mentioned.

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