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

Annotations already establish readOnly/idempotent/non-destructive, so the bar is lower, and the description still adds real behavior: the computation base rule (higher of price vs. appraisal/cadastral value), the 'not computed' fallback for unsupported municipalities, and the notary-fee exclusion. It does not describe the shape of the returned figure, which keeps it from a 5.

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?

Front-loads the country and the verb, then adds scope and caveats. The long illustrative municipality list costs some space, but it genuinely helps the agent match the free-text municipality parameter, so it mostly 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?

With no output schema, the description carries the burden of explaining returns, and it does say the tool yields a computed tax/recording figure or 'not computed'. Coverage limits, base rule and exclusions are all present; only the exact output fields are left unspecified.

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 all three parameters are documented there, so the baseline is 3. The description restates the base-value rule (higher of price and appraisal/cadastral value), which is useful context but largely duplicates the schema's own note that the value applies 'if higher than the price'.

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 (computes) and specific resources (Mexican property acquisition tax ISAI/ISABI/ISTD plus the state deed-recording fee) with an explicit geographic scope of 54 municipalities. An agent can distinguish this from closing_costs_us, purchase_costs_es or frais_notaire_fr without opening any 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?

Gives clear context: coverage of 54 named municipalities, an explicit out-of-scope signal ('others return "not computed" with no figure'), and an exclusion ('Notary fees are not computed') that implicitly routes notary questions elsewhere. It stops short of naming an alternative tool explicitly, so it is a 4 rather than a 5.

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