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

Annotations already declare readOnlyHint and idempotentHint, so safety is covered. The description adds valuable behavioral context: scoping to an identifier (anonymous IP, BYO key hash, or account ID) and the dual behavior of retrieving versus listing. No contradictions with 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, front-loaded with the core action, and every clause earns its place. It efficiently communicates the operation, usage scenarios, scoping, and related tools without repetition or filler.

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 covers the main behaviors, scoping, and sibling relationships. It doesn't specify return format or missing-key behavior, but the absence of an output schema makes that less critical; the description is sufficient for correct invocation.

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 description coverage is 100% for the single optional 'key' parameter, so the baseline is 3. The description adds extra semantic detail by giving concrete examples of stored content (target ticker, address, research notes) and reinforcing the omit-key-lists-all behavior, which goes beyond the schema.

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 (omit the key argument).' It clearly distinguishes the read/lookup nature of recall from sibling tools remember and forget, which write and delete.

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 gives explicit scenarios for use ('look up context the agent stored earlier'), states when to omit the key for listing all keys, and mentions pairing with remember/forget. It does not explicitly state when not to use it, but the context is clear enough for an AI agent to decide.

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