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

With readOnly/idempotent/non-destructive already covered by annotations, the description adds substantive domain behavior: رد and ورود نقص treatment, no عول under Shia law, the one-third bequest cap, a flagged special rule for a wife's share of land, and the return format (fraction + amount in rial with applied articles).

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-loaded with the core action and organized into purpose, routing, and input rules; every sentence carries information. It is dense with parenthetical Persian legal terms and stacks several caveats, which slightly slows scanning but does not waste words.

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 22-parameter legal calculator with an output schema, the description supplies the routing, the input-population rules, the jurisdictional caveats, and the unit/calendar conventions (rial, Jalali) an agent needs. Return values are already covered by the 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%, so the baseline is 3; the description earns above that by adding a genuinely non-obvious input rule that the schema does not encode ('a later class inherits only when every earlier class is empty', spouse inherits alongside every class). It still does not clarify the spouse/wives interaction or mother_blocked semantics beyond the schema.

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+resource (divide a deceased person's net estate among heirs) and qualifies it with the legal framework (Civil Code classes, fixed shares فروض, رد/ورود نقص, no عول, one-third bequest cap). It is unmistakably distinct from monetary siblings such as calculate_diya, calculate_mehrieh, and calculate_court_fee.

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?

Explicitly states when to use it ('when the question is who inherits how much') and where to go otherwise ('for the articles behind a share use search_iranian_law or get_law_article'). It also gives the calling rule for heirs: only living heirs, earlier classes block later ones, spouse inherits with every class.

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