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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows it's a safe read operation. The description adds valuable context beyond the annotations: it shows an 'interactive widget', is the final tool call for these requests, and warns against chaining with lookup_reciters. This extra behavioral detail justifies a score above the baseline.

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?

Every sentence earns its place: the first establishes default usage, the second gives example queries, the third clarifies finality, the fourth describes the widget, the fifth gives two precise exceptions, and the final sentence is a decisive fallback. It is longer than average but dense and well-structured, with no fluff.

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 the tool has no parameters, a rich output schema (not shown but stated as present), and clear annotations, the description fully covers when and how to use it. It explains the widget behavior, the finality of the call, and decision rules versus lookup_reciters, leaving no ambiguity for an agent.

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 tool takes no parameters (schema coverage 100% with empty properties). Per the rubric, zero parameters warrant a baseline of 4. The description appropriately emphasizes behavior rather than parameter details, which would be redundant.

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 lists Quran reciters in an interactive widget, using a specific verb ('list') and resource ('reciters'). It explicitly distinguishes itself from the sibling tool lookup_reciters by positioning itself as the default for user-facing queries and by detailing when the alternative should be used.

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?

Extremely explicit guidance: starts with 'DEFAULT tool for user-facing reciter-listing questions' and provides concrete examples ('what reciters are available', 'who can recite for me'). It clearly states when NOT to use it (plain text/raw data, or when piping to another tool) and names the alternative (lookup_reciters).

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