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

Annotations indicate idempotentHint=true, destructiveHint=false. The description adds context beyond annotations by explaining the persistence model (persistent for authenticated users, 24h for anonymous sessions) and the scope by agent identifier. However, it doesn't discuss potential side effects or rate limits, which are relevant for a write operation.

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 concise at 4 sentences, each serving a clear purpose: purpose, usage scenario, technical details, and sibling references. It could be slightly tighter (e.g., merging the second and third sentences), but overall well-structured and front-loaded.

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?

The description covers all important aspects for a simple key-value store tool: purpose, when to use, storage mechanics, persistence, and relationship with sibling tools. No additional context is needed given the tool's simplicity and the annotations provided.

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?

With 100% schema description coverage, the baseline is 3. The description adds value by providing naming conventions for keys (e.g., 'subject_property') and clarifying that values can be any text. This goes beyond the schema's generic descriptions.

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's purpose: 'Save data the agent will need to reuse later.' It uses specific verb ('Save') and resource ('data'), and distinguishes itself from siblings like 'recall' and 'forget' by mentioning them explicitly.

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 guidance on when to use the tool: 'when you discover something worth carrying forward.' It also explains the storage mechanic (key-value pair, scoped by identifier), persistence details (authenticated vs anonymous), and direct alternative tools ('Pair with recall to retrieve later, forget to delete').

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