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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered; the description adds that output is Markdown with three named sections, which helps an agent decide how to present results. It says nothing about errors for an invalid slug, response size, or whether content is cached, so it adds only modest value beyond annotations.

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?

A single compact clause with zero filler, and the key details (format and content) are front-loaded. Its terseness borders on under-specification for an agent unfamiliar with the domain, but nothing is wasted.

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-parameter read tool with full schema coverage and readOnly annotations, the description supplies what the structured data cannot: what the returned sermon actually contains and in what format, which matters since there is no output schema. Only error and size behavior are left unaddressed.

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 schema already explains that the slug comes from list_sermons, so the baseline is 3. The description adds no further meaning about the slug format or lookup behavior.

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 names the resource (one sermon) and specifies the return format and content sections (verse, short text, practice), which is more informative than the title's restatement. It does not explicitly contrast itself with list_sermons, though the singular 'one sermon' implicitly distinguishes it from a listing tool.

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 when-to-use guidance, no stated preconditions, and no mention of how to obtain a valid slug. The schema's slug field does point at list_sermons, which carries some of that burden, but the description itself offers no routing guidance versus ask_preacher or the listing tool.

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