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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description usefully adds that valuation depends on 'live gold and silver prices', implying market-dependent (non-stable) output, but omits the nisab default, the 2.5% rate basis, and how shares are treated. Note a mild tension with openWorldHint=false, since fetching live prices implies an external data source, though this is not a clear contradiction.

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?

Two short fragments, front-loaded with no filler and no repetition. It is efficient, though arguably too terse given the tool's complexity.

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?

This is a complex, 13-parameter financial calculation with no output schema, so the description should hint at what is returned (zakat amount, nisab applied, etc.). It says nothing about the result, methodology, or how the calculation resolves the many optional inputs, leaving a significant gap for an agent trying to set expectations.

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 all 13 parameters (including enum defaults for nisab and currency) are already documented by the schema. The description only lists asset classes at a high level, adding no syntax, defaults, or unit guidance beyond what the schema provides; 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?

The description states the resource (zakat owed on cash, gold, silver, shares, business stock) but is essentially the tool title reworded, with no computing verb ('calculate') to define the action. It conveys the domain clearly enough to guess the operation, but offers no differentiation from sibling mizan_screen_company, mizan_screen_portfolio, or mizan_purify_dividend.

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?

There is no when-to-use guidance and no named alternatives. An agent is left to infer that this is the calculator versus the screening or dividend-purification tools in the same family, with nothing in the text to confirm or exclude it.

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