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

Despite annotations (readOnlyHint, idempotentHint, destructiveHint) already indicating a safe read operation, the description adds meaningful context: it is 'scoped to your identifier' and that the key is optional, enabling listing. This goes beyond the annotations and helps the agent understand data isolation and dual behavior.

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 concise sentences lead with the main action, then add usage context and pairing hints. Every sentence carries weight, with no filler or repetition.

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 single-optional-parameter retrieval tool, this description is complete: it states the action, the use case, the scoping, and the relationship to sibling tools. The annotations already declare the operational safety, so the description needs no further elaboration.

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 description covers the 'key' parameter 100% (omit to list all). The tool description adds practical examples like 'the user's target ticker, an address, prior research notes' and reiterates the omission behavior, which strengthens comprehension beyond the schema alone. Though not essential, it provides useful semantic context.

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 states a specific action: 'Retrieve a value previously saved via remember, or list all saved keys'. This clearly distinguishes it from sibling tools like remember (save) and forget (delete), and includes the exact behavior of omitting the key to list all keys.

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 explains when to use it: 'Use to look up context the agent stored earlier... without re-deriving it from scratch.' It also points to sibling tools by saying 'Pair with remember to save, forget to delete.' However, it does not explicitly state when not to use it or list alternative lookup tools, stopping short of a 5.

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