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

The annotations already indicate an idempotent, non-destructive write, and the description adds valuable context beyond that: storage scoped by identifier, authentication-based persistence vs. 24-hour anonymous retention, and the key-value pair model. This covers retention and scoping without contradicting annotations.

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, front-loaded with the primary action, and every sentence contributes: what it saves, when to use it, how storage works, and how it relates to siblings. No wasted words.

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 write tool with two required params and no output schema, the description fully covers purpose, usage, retention behavior, and relationships to recall/forget. The annotations handle idempotency and safety, and the description covers all else needed for correct 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?

Schema coverage is 100% with descriptive parameter names and examples. The description reinforces the key-value pair model and adds context about 'any text' for values and identifier scoping, slightly going beyond the schema. It adds a bit of extra meaning without needing to compensate for gaps.

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 a specific verb ('Save data') and resource ('data the agent will need to reuse later') and distinguishes itself from siblings by mentioning 'across this conversation or across sessions' and pairing with recall/forget. It is immediately obvious what the tool does and how it differs from related tools.

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?

Explicit guidance is provided: 'Use when you discover something worth carrying forward' with concrete examples. It also names alternatives and companions: 'Pair with recall to retrieve later, forget to delete,' clearly telling when to use this tool vs. alternatives.

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