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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds meaningful context beyond that by explaining the scoping to an identifier (anonymous IP, BYO key hash, or account ID) and the behavior of listing all keys when the key argument is omitted.

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. It includes targeted examples, scoping, and pairing with related tools, with no superfluous information. It is slightly longer than minimal but every sentence earns its place.

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 simple one-parameter tool with no output schema, the description adequately covers how to use it, what it returns (a value or list of keys), and important contextual details like scoping and the remember/forget pairing. It is complete for the tool's complexity.

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?

Input schema already provides 100% coverage, describing the key parameter and noting 'omit to list all keys.' The description adds examples of key values (e.g., user's target ticker) but does not provide any additional parameter syntax or format details, so the baseline 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 opens with a specific verb+resource: 'Retrieve a value previously saved via remember, or list all saved keys.' It clearly distinguishes itself from siblings like 'remember' (save) and 'forget' (delete), and includes concrete examples of use cases.

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 usage context: 'Use to look up context the agent stored earlier... without re-deriving it from scratch.' It implicitly covers when not to use (i.e., for new information) and mentions the related tools remember and forget, though it does not explicitly name alternatives or exclusions.

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