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

Annotations already indicate non-read-only, idempotent, and non-destructive. The description adds valuable context about persistence ('Authenticated users get persistent memory; anonymous sessions retain memory for 24 hours') and scoping by identifier, going beyond annotations. It does not mention overwrite behavior, but idempotentHint covers that implicitly.

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 three sentences, front-loaded with core purpose, then usage guidance, then behavioral details and alternatives. Every sentence provides distinct value with no 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 key-value write tool with 2 required parameters, the description covers purpose, usage, persistence, scoping, and sibling relationships. It does not mention the return value, but given the tool's simplicity and the presence of annotations, this is a minor omission.

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 parameters, so the baseline is 3. The description echoes the schema's key-value concept and provides examples, but adds no new parameter-specific semantics beyond what the schema already contains.

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, specifying verb ('save') and resource ('key-value pair'). It distinguishes from siblings by naming recall and forget, and provides concrete examples of what to store (ticker, address, preference).

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 explicit guidance on when to use ('Use when you discover something worth carrying forward') and names alternatives ('Pair with recall to retrieve later, forget to delete'). However, it does not explicitly state when not to use, which prevents a 5.

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