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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, so the safety profile is clear. The description adds valuable behavioral context: scoping to identifier (anonymous IP, BYO key hash, or account ID) and the dual behavior (value retrieval vs. key listing). 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, front-loaded with the core action ('Retrieve a value...'), and every sentence adds value: purpose, use case, scoping, and pairing. No redundant or unnecessary text.

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?

Given the tool's simplicity (single optional parameter, full annotations, and clear sibling context), the description is complete. It explains what the tool does, when to use it, how it behaves, and how it relates to other tools.

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% (one parameter fully described). The description adds meaning by explaining that omitting the key lists all keys, which is not explicit in the schema. It does not detail return format, but this is sufficient for the simple parameter.

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 saved values or lists keys, with specific verbs ('retrieve', 'list') and resource ('value previously saved via remember', 'saved keys'). It distinguishes from sibling tools 'remember' (save) and 'forget' (delete) by its lookup function.

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 for use: 'look up context the agent stored earlier... without re-deriving it from scratch.' It mentions pairing with remember and forget, but does not explicitly state when not to use it or provide alternatives beyond siblings.

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