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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds valuable context: publication frequency (each Macau business day), default range, and the ~1 year history limit. It does not contradict annotations. The description could go further by specifying the response structure, but the added context about time ranges and defaults is substantive beyond annotation coverage.

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 three sentences, dense with information: definition, publication context, default behavior, parameter limits, and example queries. It is front-loaded with the core purpose and follows with usage specifics. No fluff or redundant statements—every sentence earns its place.

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?

The tool is simple (2 optional parameters, no output schema, annotations cover safety). The description covers definition, return value unit (percent), time range, date format, and max range. However, it does not explicitly describe the response shape (e.g., whether a single value or a series is returned). Given the absence of an output schema, this is a minor gap, but the example queries imply both single-value and historical series. Overall, enough is provided for correct invocation.

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% (both begin and end are documented), so baseline is 3. The description adds meaning by explaining default behavior (6 days before end for begin, most recent fixing for end) and the ~1 year limit, which is not in the schema. This goes beyond the schema's parameter descriptions and helps an agent construct valid calls.

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 identifies the tool as the MONIA overnight interbank reference rate, names the publisher (AMCM), and frames it as the MOP equivalent of SOFR/HONIA. It specifies the resource (overnight index average in percent) and distinguishes it from generic rate tools by including example queries like 'Macau overnight interbank rate' and 'MONIA rate today'. This is a specific verb+resource scope that differentiates it from siblings such as macau_fx_rates.

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 provides clear usage context: defaults to the last 7 days, supports begin/end date parameters, and limits to ~1 year per call. It lists example queries to signal when this tool is appropriate. It does not explicitly name alternatives or state when-not-to-use, but the context is strong enough for an agent to infer applicability (e.g., for pataca-denominated instruments).

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