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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld=false), so the bar is lower; the description adds real behavioral context by disclosing the two-stage process (business/excluded-industry screen, then AAOIFI, Dow Jones, S&P and MSCI debt screens) and that results include links to halal alternatives. No output schema exists, so this return-value disclosure is genuinely valuable.

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 question and then the screening detail, with no filler. The only slight waste is the opening sentence repeating the title verbatim, which costs a few tokens without adding 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?

For a one-parameter tool with no output schema, the description does enough: it explains the input flexibility and the shape of the answer (per-standard screens plus alternative suggestions). It could go one step further by stating explicitly what the response contains per standard, but nothing essential 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 coverage is 100%, so the parameter is already documented as a US ticker (AAPL, TSLA); the description adds meaning beyond the schema by noting a company name is also accepted and giving examples (nvidia, philip morris). That is a useful expansion of the accepted input format rather than a restatement.

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 ('Screens a US-listed stock via Mizan') and details the screening pipeline, which distinguishes it from the fund, crypto and product-checking siblings. The scope word 'US-listed stock' is enough for an agent to route correctly without opening any schema.

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 description implies when to use it ('A company name also works (nvidia, philip morris)') by clarifying accepted inputs, but never names when to prefer a sibling such as check_fund or check_crypto, nor any exclusion. Usage is inferable but not explicitly routed.

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