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

Annotations already declare the tool read-only, idempotent, and non-destructive, so the description only needs to add context beyond those. It does so by explaining scoping ('Scoped to your identifier (anonymous IP, BYO key hash, or account ID)') and the behavior of omitting the key to list all keys. 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?

The description is three sentences, front-loaded with the core action and parameter behavior. Every sentence adds distinct value: the retrieval/list behavior, the use case, and the scoping/relation to sibling tools. No redundancy or filler.

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 this is a simple one-optional-parameter tool with no output schema and rich annotations, the description covers all essential aspects: how to retrieve, how to list all, when to use it, scoping, and sibling tool relationships. An agent has enough information to invoke it correctly without further clarification.

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?

The sole parameter 'key' is fully documented in the schema (100% coverage), and the description reinforces the same behavior. It adds illustrative examples (ticker, address, research notes) but no substantive new meaning beyond what the schema already 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 opens with a specific verb ('Retrieve') and resource ('value previously saved via remember'), then clearly distinguishes the two modes: retrieve by key or list all saved keys when the argument is omitted. It is easy to tell apart from sibling memory tools like remember and forget.

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?

It explicitly states when to use the tool ('look up context the agent stored earlier... without re-deriving it from scratch') and names the paired alternatives: 'Pair with remember to save, forget to delete.' This gives clear context and exclusions for alternative tools.

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