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

The description explicitly discloses a non-obvious side effect: the tool consumes saldo as service DATO, which aligns with readOnlyHint=false and idempotentHint=false. This goes beyond what annotations alone indicate by explaining the cost model and pointing to the pricing sibling. It does not discuss output format or limits, but the main behavioral risk is covered.

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 two dense sentences with no filler. It front-loads the core purpose and immediately adds the critical cost/balance information and a pointer to the pricing tool. Every clause adds value.

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 four parameters with no schema descriptions, no enums, and no output schema, the description leaves important gaps: possible values for 'tipo', the meaning of 'subtipo', expected result format, and error/insufficient-balance behavior. The examples help but do not fully compensate for the absence of structured parameter documentation.

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 partially does so by implying 'clave' for SPEI, 'numero' for phone/LADA, and 'tipo/subtipo' for SAT catalog categories, but it never formally defines each parameter, valid values, or how they combine. Required 'tipo' remains underspecified.

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 uses the specific verb 'Consulta' and clearly identifies the resource as official Mexican catalogs/data, listing concrete examples such as SPEI bank codes, SAT catalogs, and phone/LADA lookups. This makes the tool's purpose understandable and differentiates it from generic validators, though it does not explicitly name sibling distinctions.

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 clear context: use this tool for official Mexican catalog/datum lookups and mentions that it consumes balance, directing the agent to consultar_precios for current pricing. It lacks explicit exclusions or comparisons to sibling validators, but the intended usage is clearly stated.

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