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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, covering the safety profile. The description adds valuable behavioral context: scoping to an identifier (anonymous IP, BYO key hash, or account ID) and the list-all-keys behavior when the key is omitted. No contradiction 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, each with a clear purpose: function, use cases, and scoping/relationships. It is front-loaded with the primary action and contains no filler or redundant restatement of the schema.

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-optional-parameter tool with robust annotations and a clear schema, the description provides sufficient context for selection and invocation. It explains both retrieval and listing modes. It does not specify return format or missing-key error behavior, but this is not critical given the simplicity and the presence of an output schema (or lack thereof).

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% and the property description already explains the 'omit to list' behavior. The description enriches this with concrete examples of keys (user's target ticker, address, prior research notes) and reinforces the meaning of 'key' as a previously saved memory key, adding value 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?

The description uses a specific verb ('Retrieve') and resource ('a value previously saved via remember') and clearly distinguishes two modes: retrieving a single value and listing all keys. It also positions the tool relative to sibling tools by naming remember and forget, 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 states when to use the tool ('Use to look up context the agent stored earlier') and provides a clear contrast to re-deriving information. It mentions paired tools (remember to save, forget to delete), but does not include explicit exclusionary criteria or alternatives for other lookup scenarios.

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