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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds real behavioral context beyond that: it reads the latest SEC holdings report and screens every holding by industry and debt, and explains the UK fallback path. It does not say what happens for unsupported or ambiguous tickers.

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?

Purpose is front-loaded and the length is justified by the non-obvious resolution logic. The final sentence is dense (a long list of ETF examples and index-holdings fallback) and could be tighter, but every sentence carries information.

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 should indicate what the agent receives back, but it never states that a halal/haram verdict (or screening rationale) is returned. It also omits error behavior for unknown tickers. The method coverage is good, so it is adequate but has clear gaps for a single-param decision 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% and there is only one parameter, so the schema already carries the semantics — baseline 3. The description restates that tickers and Shariah fund names are accepted, which the schema's own description already conveys, so little is added.

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 and resource ('check fund'), names the asset classes covered (fund, ETF, pension fund), and explains the mechanism (Shariah recognition by name/ticker, SEC holdings screening). It implicitly separates itself from halalornot_screen_stock and halalornot_check_crypto by scope, though it never names those siblings as alternatives.

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 through the geographic/coverage detail — US-registered funds screened directly, UK-listed ETFs routed via an index-tracking US fund — which tells the agent when this tool can answer. However there is no explicit when-to-use/when-not guidance and no mention of the sibling screen_stock tool an agent might otherwise pick.

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