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

Discloses important behavioral traits not covered by annotations: memory is scoped by identifier, authenticated users get persistent memory, anonymous sessions retain for 24 hours. The idempotentHint is consistent, and the description adds key-value storage semantics.

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 four sentences, each earning its place: purpose, usage trigger, storage mechanics, and companion tools. Well structured and front-loaded with the core action.

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 two-parameter tool with strong schema and annotations, the description fully covers usage scenarios, retention behavior, and relationships to siblings. No output schema is needed, and no gaps remain.

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%, so baseline is 3. The description adds value by explaining that the value can be 'any text' and that storage is 'scoped by your identifier,' reinforcing the key-value model beyond the schema's field 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 a specific verb ('save') with a clear resource (data/memory) and differentiates from sibling tools like recall and forget by explicitly pairing with them.

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 when-to-use guidance: 'Use when you discover something worth carrying forward' with concrete examples (resolved ticker, address, preference). It also references alternatives/complements: '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.