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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered structurally. The description adds genuinely new behavioral context: the unlock condition 'available after lighting' and the one-draw-per-day limit, though 'never draws a second oracle' partly restates idempotentHint.

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 short sentences, zero waste, with the access prerequisite and the idempotency constraint front-loaded in that order. Nothing is repeated or padded.

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 zero-parameter, fully annotated read tool with no output schema, the description supplies the prerequisite state and the call-frequency constraint an agent needs to invoke it correctly. It does not describe what the oracle returns, which would be the only remaining (minor) gap given no output schema exists.

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 there is nothing for the description to disambiguate. The schema is closed (additionalProperties: false) and full coverage is irrelevant here; baseline 4 applies for a parameterless 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?

States a specific verb+resource ('Read today's reviewed oracle') that an agent can act on directly, and the 'today's reviewed' scope narrows it against the other ritual siblings. It does not explicitly name a sibling it is not, but the resource is distinct enough from find_shrine, light_incense, make_wish, my_status, and register.

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?

'Available after lighting' gives a clear preconditional context that ties the tool to the light_incense sibling, and 'never draws a second oracle' signals the once-per-day constraint. It stops short of naming alternatives or saying what to do when the precondition is unmet, so it is clear context rather than full when/when-not guidance.

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