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

Annotations already cover safety (readOnlyHint=true, destructiveHint=false, idempotentHint=true), so the description adds credit-worthy context: the fixed set of seven topics, that each entry carries a description and an external link, and that it takes no input. It is consistent with the annotations and supplies return-shape details that annotations cannot.

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?

Two sentences with no filler: the first states purpose and output format, the second states when to use it and how it relates to find_prayer, and the closing "Takes no input" handles parameter expectations. Every sentence earns its place and the key facts are front-loaded.

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 parameterless, read-only, idempotent tool with no output schema, the description covers purpose, usage timing, sibling relationship, output structure, and input expectations. An agent has everything needed to decide when to call it and what to expect back, so nothing 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?

With zero parameters the baseline is 4, and the description explicitly states "Takes no input," which removes any doubt about whether hidden inputs or body payloads are required. There is nothing more the schema or description could add since the schema is an empty object.

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: "Lists the seven topics Sanctuary's prayer library is organized by," and details the output shape (one-line description plus link). It differentiates from the sibling find_prayer by positioning this tool as the source of valid topic values, so an agent can distinguish them without inspecting schemas.

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?

The second sentence gives explicit when-to-use conditions: when the user asks what kinds of prayers Sanctuary has or which topics it covers. It also provides a workflow directive — use it to see valid topic values before calling find_prayer — which names the follow-up sibling and tells the agent how this tool fits into a multi-step task.

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