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

Annotations (readOnlyHint=true, destructiveHint=false) are consistent with retrieval. The description adds scoping ('Scoped to your identifier') and behavior when key is omitted ('list all saved keys'), which adds value 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 composed of four efficient sentences, each adding value. The first sentence immediately states the action and variation, followed by usage context, scoping, and pairing with siblings. No redundant words.

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 retrieval tool with no output schema, the description adequately covers return behavior (value or list of keys), scoping, and integration with siblings. Missing error handling (e.g., key not found) but not critical for basic usage.

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 input schema has 100% coverage with a description for the key parameter. The description adds behavioral semantics: 'omit the key argument to list all keys', which clarifies usage beyond the schema's property description.

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 specifies the verb 'retrieve' and resource 'value previously saved via remember', and distinguishes from sibling tools (remember, forget). It also provides concrete examples like 'user's target ticker, an address, prior research notes'.

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: 'to look up context the agent stored earlier… without re-deriving it from scratch'. It also mentions pairing with remember and forget, though it does not explicitly list alternatives or when not to use.

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