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

Annotations already indicate idempotency and non-destructiveness, and the description adds valuable context beyond them: key-value scoping by identifier, persistent memory for authenticated users, and 24-hour retention for anonymous sessions. This helps the agent understand durability expectations without contradicting the annotation hints.

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 the core purpose, then usage guidance, then behavioral details. Every sentence contributes new information—there is no redundancy or filler—making it concise and easy to parse.

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 two-parameter, well-schematized tool, the description covers the essential aspects: what to store, why, persistence behavior, and related tools. It does not explicitly mention overwrite behavior on duplicate keys, but the idempotentHint annotation and the simplicity of the tool make this omission minor. Overall, it is complete enough for correct selection and invocation.

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?

The input schema already covers both parameters (key and value) with descriptions and examples, so the schema carries the semantic weight. The description adds the high-level 'key-value pair' concept and scoping, but does not elaborate on parameter format beyond what the schema provides. The 100% schema coverage justifies the baseline score of 3.

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 uses a specific verb ('Save') and resource ('data the agent will need to reuse later'), and clearly distinguishes the tool from its siblings by explicitly pairing it with 'recall' and 'forget'. This makes its role in the memory tool family unambiguous.

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 concrete, actionable guidance: 'Use when you discover something worth carrying forward... so you don't have to look it up again.' It does not name explicit alternatives or exclusions, but the sibling pairings and examples imply when to use it, which is sufficient for a simple memory-write tool.

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