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

Annotations already establish readOnly, non-destructive and closed-world, and the description adds substantial behavior beyond that: result ordering tiers, the per-verse `match` classification, `phrase_total` counting, text-language rendering, and refusal of editions whose licence forbids redistribution. The KJV-versification caveat is unusually candid about a subtle correctness issue, which is exactly the kind of context annotations cannot convey.

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 ordering rules are front-loaded well, but the text is a single dense block that packs licence policy, language rendering and edition-numbering edge cases into one wall of prose. The final sentence about Ukrainian, Douay-Rheims, Geneva, Swedish and Serbian Psalm numbering is legitimate but peripheral enough to trim or move to a help tool.

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 no output schema, the description carries the burden of explaining returns and does so: it documents `match` values, `phrase_total`, ranking rationale and ordering guarantees. Combined with the language and versification notes, an agent has everything needed to call and interpret this 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?

Schema coverage is 100%, so baseline is 3, but the description adds real meaning: `query` must be phrased in English even when `lang` selects another edition, and `lang` governs only returned text while book/chapter/verse stay KJV-numbered. It does not restate the `limit` default or maximum, leaving that to 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 opens with a specific verb and resource: 'Fast keyword search of the KJV', plus the useful scoping detail that the index is English-only. It implicitly distinguishes itself from retrieval siblings like get_verse_text or search_topic_verses by framing the operation as keyword matching, but it never names an alternative, so the differentiation is by implication rather than explicit contrast.

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?

It thoroughly describes how a query is interpreted (phrase-first, then all-words, then related) and states the edition default and when to pass `lang`, which is genuine usage context. However, it gives no guidance on when to choose this tool over siblings such as search_topic_verses or get_verse_text, and no exclusions or limits on what queries work poorly.

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