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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered and the bar is lower. The description adds that the source is specifically the Sahih al-Bukhari collection, which is genuinely useful behavioral context. It does not say what a result looks like, whether text is returned in full or excerpted, or what happens with an out-of-range book number.

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?

One short sentence, front-loaded with the action and the source collection, with no filler. It is efficient but arguably too thin for a tool whose siblings overlap heavily.

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-optional-parameter read-only tool this covers the essentials, and no output schema is needed since it returns a hadith. However, the unresolved overlap with islam_saying and the contradictory title mean an agent still lacks what it needs to choose this tool confidently.

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 description coverage is 100% and the single parameter already carries the note 'Book number within Sahih al-Bukhari. Omit for the collection'. The description's phrase 'optionally from a given book' merely restates that. Baseline 3 applies when the schema does the explanatory 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 states a specific verb and resource: look up a hadith from Sahih al-Bukhari, with optional narrowing by book. That is far more informative than the tool name alone. It loses a point because it never distinguishes itself from close siblings such as islam_saying, islam_search, or prayer_verse, and the title 'Prayer times for prayer' points at a completely different capability.

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?

There is no guidance on when to use this rather than islam_saying, islam_verse, prayer_reflection, or prayer_search, all of which plausibly retrieve similar religious text. The only usage hint is 'optionally from a given book', which is a parameter note rather than a selection criterion.

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