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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, covering the safety profile. The description adds valuable behavior beyond that: the default summary shape, the option to request 'full' vault sheets inline, and the note that results are play-side refs. No contradictions with 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?

Two sentences, no filler. The core action and resource come first, followed by the key pairing guidance and the default-vs-full behavior, all in under 50 words.

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?

A simple list-style tool with an output schema, full parameter coverage, and safety annotations. The description covers what the agent needs: what it lists, how to get full character data, and the optional detail behavior. Nothing essential 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?

Schema description coverage is 100%, so both campaignId and detail are already well documented in the schema. The description adds a tiny bit of context about output shape but does not meaningfully expand parameter semantics beyond what the schema provides.

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 clearly states the verb ('List') and resource ('characters participating in a play campaign'), and clarifies that these are play-side character refs rather than full vault data. This distinguishes it from related tools like vault_get_character or play_list_my_characters.

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 gives actionable context: use this to list campaign character refs, then pair with vault_get_character for full data. It doesn't explicitly name alternatives or when-not-to-use conditions, but the pairing guidance effectively routes the agent to the correct workflow.

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