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

Goes well beyond the annotations: discloses the one-owner-credit cost on first retrieval, that repeats are free across the owner's keys, that missing records yield a tombstone rather than an error, and adds a prompt-injection warning. This also explains the readOnlyHint=false annotation — a lookup that spends a credit is not side-effect free.

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?

Three tight sentences, front-loaded with the payload, then cost model, then failure mode, then safety warning. No sentence is filler and none bury the lead.

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 return-value burden and does so well (claim, provenance, evidence, tombstone). The remaining gap is where an id comes from, which matters given a mandatory id parameter and a sibling search tool.

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 coverage is 50% (agentKey documented, id has only a UUID format). The description implies id-lookup and tombstone behavior for unavailable ids, which partially compensates, but never states that id is a knowledge-record UUID obtained elsewhere or how to source it.

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 ('Retrieve') and names exactly what comes back: the claim, provenance and evidence. Read alone it is distinguishable from a search tool, though it never explicitly contrasts itself with search_knowledge, which is assumed to be how an ID is obtained.

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?

No when-to-use or when-not guidance, and no mention of search_knowledge as the path for discovering an ID (this tool requires an id as input). The credit-cost sentence informs the decision to use it but is not usage routing.

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