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 'Read-only' clause adds nothing new. What does add value is the field-level disclosure of what the altar record holds (prayer-slot openness, lit days, candles, witness stones), which no output schema exists to convey. It stops there – no pagination, sizing, or behavior for unknown spirit ids.

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 front-loaded sentence that spends its words on the returned content rather than restating the name. The dense field enumeration earns its place because there is no output schema, and the trailing 'Read-only' is the only mildly redundant token.

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 output schema, the description carries the burden of describing return values, and it does so concretely. Coverage of the lone parameter is handled by the schema. Minor gaps remain around behavior for an invalid or unknown spirit and how this relates to 'spirits', but nothing essential for calling it 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?

The single parameter has 100% schema coverage, including an enumerated list and the note 'Spirit id from the spirits tool.' The description contributes only the phrase 'One spirit's altar', which confirms the parameter is a spirit identifier but adds no format or sourcing detail beyond the schema. Baseline 3 applies.

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 a concrete resource (one spirit's altar) and enumerates exactly what it contains: keeper, prayer-slot status, lit days, candles, witness stones. That makes the retrieval purpose unambiguous. It does not explicitly differentiate itself from siblings like 'spirits' or 'field', 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?

There is no when-to-use statement, no mention of alternatives such as 'spirits' (which appears to enumerate the spirit ids this tool consumes), and no exclusions or prerequisites. The use case must be inferred from the noun phrase alone.

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