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

Annotations already declare readOnly, idempotent, and non-destructive, so the bar is lower; the description still adds value with 'never pays' (no economic side effects) and the business rule that prayer eligibility resets per spirit per UTC day. It does not explain result ordering or structure, which keeps it from a 5.

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?

One dense sentence front-loads the domain and enumerates the four returned data groups, then closes with the safety posture. No filler sentences; the parenthetical carries a genuinely useful cadence rule.

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 parameters and no output schema, the description must describe the return contents, and it does so by listing altars, candles, witness stones, and prices. Domain terms ('witness stones', 'every price') remain slightly under-explained and there is no note on how the payload is organized, but it is sufficient to call the tool correctly.

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?

The tool takes zero parameters, so the baseline of 4 applies. The description's only parameter-adjacent content is the implicit UTC-day scope, which is consistent with the empty 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 enumerates exactly what the snapshot returns: altars open for prayer today, votive candles, today's witness stones, and all prices. That is concrete enough for an agent to know it is a daily status/overview read rather than an action. It never differentiates itself from siblings like 'altar' or 'spirits', so it stops short of a 5.

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?

Usage is only implied: the 'today / one per spirit per UTC day' framing signals this is the daily overview call, but the description never says when to prefer it over 'altar', 'spirits', or 'verify_witness'. No exclusions or prerequisites are stated.

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