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

Annotations cover safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), but description adds behavioral context: key-value pair scoped by identifier, and persistence differences (authenticated persistent vs anonymous 24-hour retention). This goes well beyond annotations and sets accurate expectations.

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?

Description is efficiently written: purpose in first sentence, usage guidance and examples in second, storage semantics in third, and companion tool pairing in final sentence. No fluff or repetition; every sentence earns its place.

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 2-parameter tool with no output schema, the description provides all necessary context: what to store, when to use it, persistence behavior, and how it relates to recall/forget. It is complete and self-contained.

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 already documents both parameters with clear descriptions (key and value examples, coverage 100%). Description adds general context (what to store) but no additional parameter-level detail. Baseline 3 is appropriate since schema does the heavy lifting.

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?

Description opens with a specific verb+resource: 'Save data' and clarifies scope ('across this conversation or across sessions'). It distinguishes from sibling tools by explicitly pairing with 'recall' and 'forget', and gives concrete examples of what to store (resolved ticker, target address, etc.).

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 usage guidance: 'Use when you discover something worth carrying forward' and gives examples. Also names alternatives/companion tools: 'Pair with recall to retrieve later, forget to delete.' This clearly tells the agent when to use this tool and how it relates to siblings.

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