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

Annotations already provide readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description adds behavioral context such as scoping ('Scoped to your identifier (anonymous IP, BYO key hash, or account ID)') and the dual behavior of listing vs retrieving. No contradictions 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 long with no wasted words. The first sentence front-loads the core functionality, followed by usage context and scoping. Every sentence adds value.

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 (one optional param, no output schema), the description covers purpose, usage, parameter, scope, and sibling relationships. It could be more explicit about the return value format, but the lack of output schema makes this a minor gap.

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 description coverage is 100% for the single parameter 'key'. The description adds meaning beyond the schema by providing concrete examples (e.g., 'user_research_topic') and explaining the scope and usage pattern, compensating for the lack of additional parameters.

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's purpose: 'Retrieve a value previously saved via remember, or list all saved keys (omit the key argument).' It uses a specific verb ('retrieve'/'list') and resource ('saved keys'), and distinguishes from sibling tools 'remember' and 'forget' by explicitly mentioning them.

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 — the user's target ticker, an address, prior research notes — without re-deriving it from scratch.') and provides alternatives by referencing sibling tools: 'Pair with remember to save, forget to delete.'

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