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

Annotations already provide readOnlyHint, idempotentHint, and destructiveHint, so the description does not need to repeat safety. It adds valuable behavioral details beyond the schema: the default compact summary shape with specific fields (identification, summary, level, school, classes, categories, publisher/source) and the option to request 'full' detail. It also discloses the access scope (stock plus own house spells). This is solid context without overstating side effects.

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 are front-loaded with purpose and scope first, then response behavior. Every phrase earns its place: it avoids restating schema details while still providing the key usage and output shape. No filler or redundancy.

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 read-only search tool with 8 self-documenting parametersthis and an output schema present, the description covers everything an agent needs: what it searches, the scope of the library, the searchable fields, and the response shape options. Pagination and sorting are fully described in the schema, so their absence here is not a shortcoming.

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 the baseline is 3. The description adds meaning by explaining the response shape implied by the `detail` parameter and enumerating the summary fields, which complements the schema's concise parameter descriptions. It does not repeat every parameter, but the schema already covers them thoroughly.

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 ('Search'), a resource ('spell library'), and a clear scope ('the user has access to (stock spells plus their own house spells)'). It also names the searchable criteria (name, ruleset, type), making it unambiguous and distinct from sibling search tools like vault_search_items or vault_search_rules.

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?

Provides clear context for use: 'Use this to locate a spell or power by name, ruleset, or type.' It also clarifies the library scope, which helps an agent decide when this tool is appropriate. However, it does not explicitly name alternatives or state when not to use this tool (e.g., comparing with vault_get_spell for exact-ID lookups), so a small gap exists.

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