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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds valuable behavioral context: the tool is scoped to a user identifier (anonymous IP, BYO key hash, account ID) and that omitting the key lists all saved keys. This goes beyond the annotations without contradicting them.

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 earning its place: the first states the core function, the second provides the use case, and the third explains scoping and relationships to sibling tools. There is no redundancy or filler, and the most important information is front-loaded.

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 tool with one optional parameter and strong annotations, the description is fully complete. It covers what the tool does, when to use it, how to invoke both modes, and the scoping context. No output schema exists, but the description sufficiently implies the returned information (a value or list of keys).

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 schema already documents the 'key' parameter with 100% coverage. The description enriches this by explaining the parameter's role with concrete examples (user ticker, address, research notes) and clarifies that omitting it triggers list mode. This adds meaning beyond the raw 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 opens with a specific verb and resource: 'Retrieve a value previously saved via remember, or list all saved keys.' This clearly differentiates the tool from siblings like remember and forget, and it outlines the dual-mode behavior (retrieve by key or list all).

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... without re-deriving it from scratch.' It also names the alternative tools for related operations ('Pair with remember to save, forget to delete'), providing clear usage guidance and exclusions.

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