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

While annotations already indicate it's a write operation (readOnlyHint=false) and non-destructive, the description adds key context: 'scoped by your identifier' and 'Authenticated users get persistent memory; anonymous sessions retain memory for 24 hours'. This goes beyond annotations, though it doesn't explicitly address overwrite behavior (covered by idempotentHint=true).

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 front-loaded with the core action, then gives usage context, scope, persistence details, and sibling relationships in just four sentences. Every sentence adds distinct value without redundancy.

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 save tool, the description is quite complete: it covers persistence, scope, and complementary tools. A minor gap is the lack of return-value explanation, but for a write operation that is often obvious. The idempotentHint covers overwrite semantics.

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%, with each parameter (key, value) having a clear description. The description's 'key-value pair' phrasing adds no extra semantic value beyond the schema, so 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 clearly states the tool saves data for later reuse, using the specific verb 'Save' and identifying the resource (data/items). It also distinguishes itself from siblings by explicitly pairing with 'recall to retrieve later, forget to delete'.

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?

Explicitly says 'Use when you discover something worth carrying forward' and provides concrete examples. It also names alternatives (recall, forget) and clarifies persistence differences between authenticated and anonymous sessions.

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