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

Annotations already cover idempotency and non-destructive behavior. The description adds meaningful behavioral context: key-value pair scoped by identifier, persistence differences between authenticated and anonymous sessions, and cross-session retention. This goes beyond the structured hints, though it could state overwrite semantics.

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?

Four sentences, purpose-first, with no fluff or redundancy. Each sentence contributes value: what it does, when to use, how it works, and related tools.

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 two-parameter tool, the description covers the operation, usage context, persistence behavior, and sibling tools. No output schema exists, but the tool returns no structured output, so none is needed. The description is complete for effective use.

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 both parameters have descriptive examples. The description adds contextual scoping ('scoped by your identifier') but no new parameter syntax or format. Baseline 3 is appropriate since the schema does the heavy lifting.

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 action ('Save data'), the resource (key-value store), and the scope (across conversations/sessions). It distinguishes from sibling tools by naming recall and forget as paired 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?

Explicit when-to-use guidance is provided with concrete examples (resolved ticker, target address, user preference, research subject). It also points to alternatives ('Pair with recall... forget to delete'), giving clear context for when this tool is appropriate.

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