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

Beyond the annotations (which show a non-readonly, non-destructive, idempotent write), the description adds meaningful context: storage as a key-value pair scoped by identifier, persistent for authenticated users, and 24-hour retention for anonymous sessions. It doesn't disclose whether overwriting an existing key is allowed, but this is a minor gap given the idempotency hint.

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 with no wasted words: first states the core purpose, second gives usage guidance with examples, third explains storage mechanics and persistence. The most important information is front-loaded, and every sentence earns its place.

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 write tool with thorough annotations and full schema coverage, the description is complete. It covers purpose, usage triggers, storage semantics, retention policy, and sibling relationships, leaving no critical gaps 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 coverage is 100% and each parameter has clear descriptions and examples. The description reinforces the key-value concept but adds no new meaning beyond what the schema already provides, so the baseline of 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 and resource: 'Save data the agent will need to reuse later' and explicitly positions it as a key-value store scoped by identifier. It distinguishes from siblings by pairing with recall (retrieve) and forget (delete), making the tool's role unmistakable.

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 guidance on when to use: 'Use when you discover something worth carrying forward' with concrete examples like resolved ticker and user preference. It also names recall and forget as complementary tools, though it does not explicitly state when NOT to use remember, so it falls just short of a 5.

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