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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds meaningful behavioral context: no widget is rendered, it is internal/preparatory, there are hard limits (max 20 queries and 50 items), and it requires at least one of languages or tafsir_slugs. It also clarifies the output is text-only. This goes well beyond the annotations without contradicting them.

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 dense but every sentence serves a critical purpose: defining the tool's role, stating exclusions, listing use cases, warning against duplication, specifying requirements, and giving limits. It is front-loaded with the most important classification ('INTERNAL/preparatory tool') and structured with clear conditions (a/b) and a final preference rule. No wasted words given the complexity of the tool's placement in the workflow.

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 tool with no output schema and a single parameter, the description covers the full context: what it returns (text-only data), when it should be used, how to structure queries, and all constraints (limits, required fields, key format). It also explains its relationship to ayah_tafsir, which is essential for correct selection. There are no obvious gaps for an agent to misuse the 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?

The input schema covers 100% of the single parameter (queries) with field-level descriptions, so the baseline is 3. The description adds extra semantic value by explaining the requirement to include at least one of languages/tafsir_slugs per query, the ayah key format ('surah:ayah'), and aggregate limits (max 20 queries, max 50 items) not fully spelled out in the schema. It also clarifies that an empty array is treated as omitted, which aligns with schema descriptions. This enrichment justifies a score above baseline, though not a 5 because the schema already does most of the work.

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 identifies the tool as an internal/preparatory text-only retrieval tool, with a specific verb ('get tafsir text') and resource (Quran tafsir data). It explicitly distinguishes itself from ayah_tafsir by stating it renders no widget and is not for user-facing answers, making its purpose unambiguous and distinguishable from siblings.

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 gives explicit when-to-use and when-not-to-use guidance: use only for explicit plain-text requests or for chaining into other tools, never as a direct answer, and not after ayah_tafsir to avoid duplicated work. It names the alternative (ayah_tafsir) and even provides a preference rule ('When in doubt, prefer ayah_tafsir'), which is exemplary.

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