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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds valuable context beyond annotations by explaining the scoping mechanism (anonymous IP, BYO key hash, or account ID) and the behavior of omitting the key (list all keys). This enriches the agent's understanding of side effects and scope without contradicting 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 primary action. Every sentence earns its place: functionality, use cases, and pairing instructions. 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?

This is a simple tool with one optional parameter and no output schema. The description covers purpose, usage, scoping, and relationships to sibling tools, which is sufficient given the low complexity. Annotations cover safety, so nothing critical is missing.

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 covers the 'key' parameter with 100% description coverage, explaining that omitting it lists all keys. The description reinforces this behavior and adds context about the storage scope, going slightly beyond the schema. This additive value justifies a 4.

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 clearly states the tool retrieves a previously saved value or lists all saved keys, with a specific verb ('Retrieve') and resource (memory stored via remember). It also distinguishes itself from siblings by explicitly referencing remember and forget, making its role in the memory workflow 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 provides clear context on when to use this tool ('to look up context the agent stored earlier') and offers examples (ticker, address, research notes). It also mentions pairing with remember and forget, which implies alternatives, but does not explicitly state when not to use it or contrast with search tools.

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