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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds valuable context beyond these: scoping to an identifier (anonymous IP, BYO key hash, account ID), the ability to list all keys by omitting the key argument, and the pairing with remember/forget. This enriches the agent's understanding of the tool's behavior 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?

Three sentences, each contributing distinct value: function, usage context, and scoping/companion tools. No redundancy, front-loaded with the primary action, and free of extraneous detail. Every sentence earns its place.

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 complete. It explains both modes (retrieve by key, list all), when to use it, scoping, and sibling relationships. No output schema exists, but the description adequately conveys what the user gets back ('a value' or 'all saved keys'). No critical gaps remain.

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 covers 100% of parameters with a clear description: 'Memory key to retrieve (omit to list all keys)'. The description essentially repeats the same information ('omit the key argument'), adding little semantic value beyond what the schema already provides. The bar is met but not elevated.

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-resource pair: 'Retrieve a value previously saved via remember, or list all saved keys.' It clearly distinguishes from siblings like remember and forget by explicitly naming them and associating recall with retrieval. The purpose is unambiguous and the tool's scope is well-defined.

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?

Provides explicit when-to-use context: '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.' It also pairs with remember and forget, indicating alternatives for save/delete operations, and mentions the optional key-omission behavior for listing all keys. This fully answers when and when not to use it.

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