INPC México

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

The description adds real behavior beyond the safety annotations: which INPC months are used at each endpoint, the fallback to the last published INPC, truncation to four decimals, and the floor of 1. With readOnly/idempotent/destructive already covered by annotations, these domain rules are the added value, though the response shape and edge-case behavior (e.g. inverted period) remain unstated.

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 dense sentence, front-loaded with the action and legal reference, with the exclusion clause last. Every clause carries information, though the mid-sentence enumeration of rules is packed and would read better as short ordered statements.

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 read-only pure-calculation tool with three documented parameters, all the computational rules an agent needs are present, and the description even hints at the return value when importe is supplied. Missing only the concrete output shape and behavior for invalid or inverted periods, which matters little given there is no output schema.

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 the baseline is 3, but the description adds meaning the schema does not: it explains that the two month parameters correspond to the INPC of the month preceding each endpoint, and that supplying importe triggers an additional updated-amount result. That mapping is not derivable from the schema alone.

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 and resource ("Calcula el factor de actualización") plus the exact legal basis (Art. 17-A CFF) and the three objects it applies to (contribución, devolución, saldo pagado fuera de plazo). It also carves out what it is not ("No calcula recargos"), which is enough to separate it from the raw INPC siblings.

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 makes clear the situation that selects this tool (late payment, refund, or outstanding balance) and explicitly excludes recargos calculation. It does not name calcular_variacion_inpc or consultar_inpc as the alternatives for raw index data, so routing is implied rather than stated.

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

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds the fiscal-scope caveat and hints at the two returned quantities, but says nothing about what happens if the months are inverted or out of range, nor about error behavior.

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 front-loaded sentence: verb, output, scope exclusion, then use cases. Dense but no wasted sentences; the parenthetical and colon chain make it slightly heavy to parse but it stays tight.

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 two-parameter, read-only calculation with full schema coverage and complete annotations, this is close to complete, especially since it names both returned quantities despite there being no output schema. The remaining gap is the unspecified behavior for invalid or inverted month ranges.

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 100% and both parameters already document the AAAA-MM format and the older/newer ordering. The description only says 'dos meses concretos' and adds no meaning beyond the schema, so the baseline of 3 applies.

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 (calcula) and resource (variación del INPC / inflación acumulada) and explicitly scopes itself against the fiscally-flavored sibling by saying it works 'sin las reglas fiscales del Art. 17-A'. An agent can distinguish it from calcular_factor_actualizacion_fiscal 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?

Names concrete use cases (ajustar rentas, pensiones, contratos indexados) and implicitly excludes the fiscal-rule variant, which routes the agent to the sibling. It stops short of naming the alternative tool or stating an explicit when-not condition.

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

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds value beyond that by naming the data source (INEGI), the index base, and the important default that omitting the month returns the most recently published value.

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?

Two tight sentences: the return value and its source/base come first, then the no-argument default, then the trigger examples. No filler, and the most decision-relevant information is front-loaded.

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 single-optional-parameter read tool with full annotations, the description covers source, base, default behavior and invocation triggers. The only omission is what the return value looks like (numeric scalar vs. structured object), which matters slightly since there is no output schema.

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% and the single 'mes' parameter already documents the AAAA-MM format and the default-to-latest behavior. The description restates the default but adds no format, range, or edge-case detail beyond the schema, so it sits at the baseline for fully documented parameters.

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 and resource: returns the INPC value published by INEGI for a given month, and pins the index base (2nd half of July 2018 = 100). This clearly separates it from siblings like calcular_variacion_inpc and calcular_factor_actualizacion_fiscal, which compute derived figures rather than the raw index, though the description never names those alternatives explicitly.

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 trigger phrasing with two concrete example questions ('¿cuál es el INPC de agosto de 2026?' and '¿cuál es el último INPC?'), which maps directly onto the two modes of the tool. It does not state when to prefer a sibling tool instead, so the routing guidance is one-sided.

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