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

With annotations already declaring readOnlyHint=true and destructiveHint=false, the description doesn't need to restate safety. It adds valuable behavioral context beyond annotations: the scoping to 'your identifier (anonymous IP, BYO key hash, or account ID)' and the ability to list all keys when the argument is omitted. This enriches the agent's understanding without contradicting the 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 only two sentences long, yet it covers purpose, usage examples, scoping, and relationships with sibling tools. Every sentence earns its place; there is no redundancy or filler. The structure is front-loaded with the core action and then contextual details.

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 read-only tool with one optional parameter and no output schema, the description is complete. It explains what the tool does, when to use it, the scoping model, and how it pairs with remember and forget. The annotations provide the safety profile, so the description doesn't need to restate that. The only minor omission is behavior for missing keys, but that is not essential for tool selection.

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 for the single optional 'key' parameter is 100%, giving a baseline of 3. The description adds meaningful semantics by explaining that the key refers to a value 'previously saved via remember' and provides concrete examples ('user's target ticker, an address, prior research notes'). It also clarifies the behavior when omitting the key (list all keys), which enhances the schema's description.

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 function: 'Retrieve a value previously saved via remember, or list all saved keys (omit the key argument).' This uses a specific verb and resource, and explicitly distinguishes the tool from siblings by referencing 'remember' and 'forget' as counterparts. The purpose is unambiguous and well-scoped.

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 usage 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 indicates how to list keys by omitting the key argument and mentions scoping. However, it does not explicitly state when not to use this tool or list alternative retrieval tools, so it stops short of full exclusionary guidance.

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