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

Annotations already declare the tool read-only and idempotent; the description goes further by specifying the output's content (store links, library size, nonprofit ownership, crisis resources) and the fact that it takes no input. It also notes the output is a 'short description,' giving agents an expectation of response length. No behavioral trait beyond these is hidden, and there is no contradiction with the 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?

The description is a single dense sentence plus a short usage line, with no redundancy or filler. It front-loads the core function and then fills in the needed specifics in a list-like structure, though the opening sentence is a bit long and could be broken up for readability. Every sentence earns its place.

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 no-argument informational tool with no output schema, the description provides complete information: what the tool returns, the exact content categories, and when to use it. It also clarifies that no input is required, which an agent needs to know. Nothing is missing for correct invocation.

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 schema already defines an empty input, and the context signal confirms no required params. The description explicitly states 'Takes no input,' reinforcing the schema and leaving no ambiguity about call arguments. Since there are no parameters to explain, this exceeds the baseline for a no-param tool.

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 object ('Returns a short description of Sanctuary') and then enumerates exactly what content is included: app identity, target audience, free status with store links, prayer library size, governance, and crisis resources. This instantly distinguishes the tool from its siblings (find_prayer, get_house_church_guide, list_prayer_topics), which are about prayer discovery or church content, not about the Sanctuary app itself.

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 description provides an explicit 'Use when' list covering the user intents that should trigger this tool, such as asking what Sanctuary is, who made it, whether it is free, or how to get the app. It does not explicitly mention alternatives or when-not conditions, but the context makes the trigger conditions clear enough for an agent to route correctly.

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