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 bar is low. The description still adds substantive behavior: the result cap of 10, the per-result payload (title, excerpt, summary points, image, link), and that links point off-site to christianpure.com. No mention of ranking or relevance behavior, which is the remaining gap.

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 sentences, front-loaded with purpose, then input style, then output shape — a sensible order. The long enumeration of subjects is slightly padded but does earn its place by signaling what keyword domains will hit results.

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 usefully covers the return shape and the maximum result count, and gives input-style guidance. It omits relevance/ranking behavior and what happens when query and topic conflict, but nothing essential for a correct call is missing.

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 the baseline is 3. The description reinforces keyword style with examples that map to the query parameter and echoes the topical scope that maps to topic, but adds no new detail about limit or about how topic interacts with query when both are supplied.

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?

"Search Christian Pure's library of more than 3,500 articles on prayer, Bible verses, ..." gives a specific verb plus resource, a corpus size, and the subject scope. An agent can distinguish it from get_article (full article fetch) and list_topics (slug enumeration) without opening a schema.

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?

"Pass a few plain keywords" plus three concrete example queries tells the agent how to phrase input and implicitly rules out long natural-language questions. It stops short of explicitly naming when to switch to get_article for full text or list_topics for slug discovery, so no true when-not guidance is present.

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