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

Annotations already declare readOnly, idempotent, and non-destructive. The description adds valuable behavioral context: listing all keys when omitted, scoping to identifier (anonymous IP, BYO key hash, account ID), and the lifecycle relationship with remember/forget. This goes beyond the annotations without contradicting them.

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 cover the core behavior, use case, scoping, and sibling pairing without repetition. Information is front-loaded: the first sentence states exactly what the tool does. No wasted words.

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, the description covers the main intent, usage scenario, and scoping. It does not detail return format or error behavior, but given the output schema is absent and the tool is straightforward, this is acceptable. A small gap remains in not stating what happens if the key does not exist.

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% and the schema description already explains the key parameter. The tool description adds the omit-to-list behavior and scoping context, reinforcing and extending the schema meaning. This exceeds the baseline 3.

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: 'Retrieve a value previously saved via remember, or list all saved keys.' This clearly distinguishes it from the sibling tools remember and forget, and the behavior is unambiguous.

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') and references the paired siblings ('Pair with remember to save, forget to delete'). It lacks an explicit when-not to use, but the guidance is sufficiently clear.

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