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

Annotations already declare the read-only, idempotent, non-destructive nature. The description adds behavioral context: scoping to the user's identifier (anonymous IP, BYO key hash, or account ID) and the ability to list all keys. This goes beyond the schema and 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, each serving a purpose: defining the action, giving use cases, and placing the tool in its family. It is front-loaded with the core behavior and avoids redundancy.

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 retrieval tool with a single optional parameter, the description covers the main functionality, scoping, and sibling relationships. It could be slightly more complete by describing the return format or error behavior when a key is not found, but this is not a significant gap given the annotations.

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 already covers the 'key' parameter with a description. The tool description adds value by explaining the omission behavior for listing all keys and providing examples of what keys are used for (ticker, address, notes). It also clarifies the scoping of keys.

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 retrieves a value previously saved via 'remember' or lists all saved keys when the key is omitted. It distinguishes itself from sibling tools 'remember' and 'forget' by naming them and contrasting save/delete operations.

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?

It explicitly says 'Use to look up context the agent stored earlier' and gives examples (target ticker, address, research notes). It names pairing with 'remember' and 'forget', clarifying when to use this instead of the alternatives.

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