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

Annotations already declare readOnlyHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description adds that output concerns source provenance and licensing, which is modestly useful context, but it doesn't disclose pagination, lookup granularity, or failure behavior.

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, front-loaded with the purpose before the usage trigger. Most words earn their place, though 'Say where a Discover answer comes from' is slightly roundabout phrasing.

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 an output schema present, return values needn't be explained, and annotations cover safety. The description supplies purpose and usage context; the only soft spot is the ambiguous 'type'/'catalogue' parameter, which neither description nor schema fully clarifies.

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% and there is only one parameter, so the schema carries the burden. The description loosely ties the lookup to 'a data type', hinting at the 'type' param, but adds no syntax, examples, or accepted values beyond the 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?

States a specific purpose — surfacing which public sources back a Discover answer and their licence. It doesn't explicitly name the sibling discover_search, but it references 'a Discover answer' which ties it to the Discover family, so an agent can distinguish it reasonably well.

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?

Gives an explicit when-to-use trigger: 'when the user asks how we know something, or whether the information can be trusted.' There is no when-not condition or named alternative, but the invocation context is clear.

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