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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds real operational context beyond that: only places with a published flatin.es page return figures, keys whose source terms disallow export answer 'not_available', and province-level fallback appears when a municipality has no data. The only missing element is an explicit error/empty-result 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?

The core scope (2–4 places, side-by-side figures) is front-loaded in the opening clause, and the dense middle section enumerates the data domains efficiently. It is a single long sentence with some list-like padding around data sources, but nothing is redundant enough to be cut without losing coverage.

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 return-value burden well: it states that each figure includes unit, period, level, source credit and date, plus station/POI distance, and that answers link the flatin.es pages. That is nearly everything an agent needs to interpret results; only explicit error/empty-result behavior is absent.

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%, so the schema already documents locale, place formats and indicator keys. The description largely restates structured constraints ('at most 12 indicators per call', province lists, buyer zone names) rather than adding new syntax or format meaning. Baseline 3 is the right call when the schema does the heavy lifting.

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 states a specific verb and resource — 'Side-by-side latest figures for 2–4 municipalities ... or buyer zones' — and enumerates the covered geography (Alicante, Málaga, Valencia, Murcia), which pins the tool's scope precisely. An agent can distinguish this multi-place comparison tool from single-figure siblings like ibi_rate or purchase_costs without opening the 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?

Usage is implied by the shape of the call: use it when comparing 2–4 places across many indicators. However, no sibling tool is named and there is no explicit 'use this instead of ibi_rate when...' routing, nor any when-not-to-use guidance, so an agent must infer the boundary itself.

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