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

Annotations already indicate non-read-only, idempotent, and non-destructive behavior. The description adds value by disclosing persistence semantics: authenticated users get persistent memory, anonymous sessions retain for 24 hours, and data is scoped by identifier. This goes beyond the structured annotations with meaningful operational context.

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 a single focused paragraph that front-loads the purpose in the first sentence. It includes necessary usage guidance, persistence details, and sibling references without excessive verbosity. Each sentence contributes meaningful information, though it is slightly longer than strictly necessary.

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 key-value storage tool with no output schema, the description is complete. It covers what the tool does, when to use it, persistence behavior, scoping, and how it relates to recall and forget. No critical context is missing for an agent to invoke it correctly.

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 both key and value parameters, so the schema already documents their meanings. The description adds generic context about key-value pairs but no additional parameter-specific details beyond the schema examples. Baseline score of 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 a specific verb+resource: 'Save data the agent will need to reuse later' and explicitly distinguishes the tool from siblings by naming recall and forget. It also provides concrete examples of what to store (ticker, address, preference, research subject), leaving no ambiguity about the tool's purpose.

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 provides explicit '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 the alternatives (recall for retrieving, forget for deleting), making the usage context crystal clear and differentiating from sibling tools.

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