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 genuinely useful behavioral context beyond that: rates come from a database, and each row's `unit` field must be read because «rials» vs «درصد» changes the meaning of the value. It does not add auth/rate-limit detail, but for a read-only lookup that is minor.

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 purpose and rate enumeration are front-loaded, followed in order by the two exclusion rules and the unit caveat. It is dense with Persian terms and caveats, but in a high-stakes legal-rate domain each sentence carries a distinct routing or interpretation instruction rather than 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?

For a two-parameter, read-only key lookup with no output schema, the description supplies everything an agent needs: the available keys, the optional-year default (also in schema), the alternatives for out-of-scope figures, and how to interpret the returned unit. Nothing material to correct invocation is missing.

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 baseline is 3. The description nevertheless adds value by listing the concrete rate keys and the court_fee_* pattern, which clarifies what rate_type accepts beyond the schema's short example list, and by pointing at the returned unit semantics for interpreting results.

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 (fetch) and resource (official Iranian yearly rates from the database) and enumerates the exact rate keys it serves (min_wage, court_fee_*, salary_tax_exemption_annual, cbi_price_index, sanavat_daily). It explicitly distinguishes itself from calculate_lawyer_fee and calculate_diyeh, so an agent can route correctly among the many calculate_* 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?

Gives explicit when-to-use ('ALWAYS use this instead of recalling a rate'), when-not (حکالوکاله is NOT an annual rate; for دیه use calculate_diyeh), and names the alternative tools by name. The conditional routing is fully spelled out rather than inferred.

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