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.