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

Annotations already declare the tool as read-only (readOnlyHint=true), non-destructive, and idempotent. The description adds valuable behavioral context: scoping 'to your identifier (anonymous IP, BYO key hash, or account ID)' and the dual behavior (retrieve by key vs list all). No contradictions with annotations. The description enhances transparency beyond 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?

The description is exceptionally concise: three sentences covering purpose, use cases, and scope. Every sentence is essential and information-dense with no repetition or fluff. Front-loaded with the core action, it is highly efficient.

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?

Given the tool's simplicity (one optional parameter, no output schema), the description provides sufficient context: retrieval mode, listing mode, scoping, and pairing with remember/forget. It could mention what happens if the key doesn't exist, but for most use cases the description is complete enough for correct invocation.

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 100% with the 'key' parameter well-described in the schema. The description reinforces that omitting the key lists all keys, but this is already in the schema description ('omit to list all keys'). Since the description adds little beyond the schema, and baseline is 3 for high coverage, a score of 3 is appropriate.

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 tool retrieves a value saved via remember or lists all keys if no key is provided. It uses specific verbs like 'Retrieve' and 'list' and identifies the resource as 'value' or 'keys'. It distinguishes from siblings 'remember' and 'forget' by pairing them, making the purpose unambiguous.

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 explicitly tells when to use the tool: 'to look up context the agent stored earlier' and provides concrete examples like 'target ticker, an address, prior research notes'. It also frames usage as an alternative to re-deriving context. While it doesn't explicitly state when not to use it, the pairing with 'remember' and 'forget' gives implicit usage boundaries.

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