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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely new context: results are citation snippets rather than full texts, and an empty result set is not evidence of absence. It does not describe ranking or ordering of results, which would be the next useful detail.

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?

Three tight sentences: capability first, then when to use, then the follow-up tool and the negative-result caveat. Every sentence carries distinct information and nothing is repeated from the schema.

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?

With an output schema present and full parameter documentation, the description only needs to cover purpose, selection criteria, and follow-up behavior — all of which it does, including the important caveat about interpreting empty results.

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%, so 'era', 'limit', 'author', and 'reference' are already fully documented in the schema. The description adds nothing about filter behavior or how era interacts with author, so the baseline of 3 applies.

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 ('Find what ... writers said about a specific Bible verse') plus the return shape ('passages that cite it, with snippets'). It also implicitly separates itself from search_writings and get_writing by framing itself as verse-indexed retrieval rather than full-text reading.

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?

Gives explicit triggering conditions ('how a verse was interpreted', 'what the early church taught', 'commentary on it') and names the alternative for the follow-up step ('Read a passage in full with get_writing'). It even addresses the negative case: 'No result is not proof a writer never discussed it.'

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