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

Annotations already indicate a non-read-only, idempotent, non-destructive operation. The description adds valuable context: 'key-value pair scoped by your identifier,' and persistence details for authenticated vs anonymous sessions. This exceeds the annotation baseline but stops short of describing overwrite behavior or error cases, which are minor for this tool.

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 well-structured and front-loaded with the core purpose. Each sentence adds meaningful information—usage scenarios, storage mechanism, retention policy, and companion tools. No filler or repetition, making it appropriately sized for the tool's simplicity.

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 write tool with 2 parameters and no output schema, the description covers all essential aspects: what it does, when to use it, persistence behavior, and integration with recall/forget. It is fully complete for its complexity.

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 covers 100% of parameters with clear descriptions and examples, so baseline is 3. The description reinforces the key-value concept but does not add syntax or format details beyond the schema. It adequately supports the agent without being redundant.

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's function: 'Save data the agent will need to reuse later.' It uses a specific verb ('save') and resource ('data'), and distinguishes itself from siblings by referencing 'recall' and 'forget' as complementary operations. This makes the purpose unambiguous and distinct.

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: 'Use when you discover something worth carrying forward... so you don't have to look it up again.' It also names alternatives: 'Pair with recall to retrieve later, forget to delete.' This goes beyond basic context and clearly directs the agent on when to invoke this tool versus related ones.

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