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

With readOnlyHint and openWorldHint already declaring the safety profile, the description adds genuine non-obvious context: the data is refreshed from Algérie Poste daily, it covers Algeria only, and it discloses geospatial and address fields returned. It doesn't cover rate limits or auth, but the freshness and scope notes are real added 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?

One front-loaded sentence that leads with the core action and then unpacks the return payload; the parenthetical field lists are long but each item earns its place by pre-empting a schema lookup. Slightly dense, but no filler.

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?

No output schema exists, so the description carries the full burden of describing return values, and it does so exhaustively (post office names in French and Arabic, class, address, postal codes, GPS; ATM name, status, postal code, GPS). Combined with the schema's error-code documentation, an agent has what it needs to call and interpret the tool.

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 both optional parameters (lang, country) and the code are fully documented in the schema, including enum values and the country_not_available/key_required behaviors. The description adds the 'four-digit, from list_communes' framing for the code but does not extend the optional parameters, so baseline 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 ('Get'), resource ('one commune of Algeria'), and lookup key ('by its four-digit code'), then enumerates exactly what is returned (names, wilaya, postal codes, post offices, ATMs). This clearly separates it from siblings list_communes and get_wilaya.

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 parenthetical '(from list_communes)' tells the agent where the required code comes from, and 'Algeria only' plus the notes about TN/MA availability set scope. It gives clear usage context but no explicit when-not guidance or alternative tool routing.

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