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

Annotations already establish readOnlyHint=true and destructiveHint=false, so the read-only safety is covered. The description adds useful behavioral context: it renders no widget, is internal/preparatory, and is intended for chaining. It does not describe the return value shape, but given the simple data-only nature, this is adequate.

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 description is concise and front-loaded: it opens with the internal/preparatory and text-only nature, then gives explicit do/don't guidance, and closes with a clear fallback rule. Every sentence earns its place; no filler or repetition.

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?

Given one optional parameter, full schema coverage, and read-only annotations, the description is fully complete. It tells exactly when to use it, when not to, how it differs from the sibling list_tafsirs, and how it fits into a chained workflow. No output schema is needed for this simple data lookup.

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?

The sole parameter 'languages' is fully described in the schema with an example ('en', 'ar'). Since schema description coverage is 100%, the description does not need to add parameter details. Baseline 3 applies because description adds no parameter-specific 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?

The description clearly states the tool is an internal/preparatory, text-only lookup for tafsir collections, and explicitly distinguishes it from list_tafsirs. The verb 'lookup' plus the resource and the 'data only' scope fully clarify what the tool does.

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 guidelines are exceptionally explicit: NEVER use as the user-facing answer, use list_tafsirs by default, and use this only for plain-text requests or when chaining into ayah_tafsir in the same turn. It even says 'When in doubt, prefer list_tafsirs,' leaving no ambiguity.

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