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

Beyond the annotations (idempotentHint=true, destructiveHint=false), the description adds critical behavioral details: key-value pairs scoped by identifier, persistence differences for authenticated vs. anonymous sessions (24 hours), and the pairing with recall/forget. This enriches the agent's understanding of storage semantics without contradicting any annotation.

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, each earning its place: sentence one states the core purpose, sentence two provides usage guidance with concrete examples, and sentence three covers persistence and related tools. Well-structured, front-loaded, and free of fluff.

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 store tool with two well-documented parameters and idempotent annotations, the description is nearly complete. It covers usage, persistence, and relationship to sibling tools. The only notable omission is explicit mention that storing to an existing key overwrites the previous value, but this is a minor gap given the idempotentHint annotation.

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 input schema already provides comprehensive descriptions for both parameters (key and value), yielding 100% schema coverage. The description adds only a minor detail ('scoped by your identifier') but doesn't materially enhance the parameter understanding beyond what the schema already conveys, so a baseline 3 is appropriate.

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 ('Save') and resource ('data the agent will need to reuse later'), clarifying its scope across conversations and sessions. It distinguishes itself from sibling tools by explicitly referencing 'recall' to retrieve and 'forget' to delete, firmly establishing its unique role in the memory suite.

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?

Provides clear when-to-use guidance: 'Use when you discover something worth carrying forward... so you don't have to look it up again.' It also names alternatives directly ('Pair with recall to retrieve later, forget to delete'), giving explicit context for when this tool is appropriate versus its siblings.

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