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

Annotations already convey safety traits (readOnlyHint=false, destructiveHint=false, idempotentHint=true). The description adds valuable behavioral context about persistence ('Authenticated users get persistent memory; anonymous sessions retain memory for 24 hours') and scoping by identifier, which goes beyond the annotations without contradicting them. It does not detail overwrite semantics for existing keys, but the annotation coverage lessens that burden.

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 and well-structured, consisting of three sentences that each serve a distinct purpose: purpose, usage guidance, and persistence/related-tool info. No filler or redundant content, making it highly efficient.

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 tool with two parameters and no output schema, the description covers all necessary context: purpose, when to use, persistence behavior, and relationship to sibling tools. It is sufficiently complete for an agent to select and invoke the tool correctly.

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 description coverage is 100%, so the baseline is 3. The description adds semantic value beyond the schema by providing examples of what to store (resolved ticker, target address, user preference) and clarifies the key-value pairing, reinforcing the parameters' meaning with concrete use cases.

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 states a specific verb ('Save data') and resource ('key-value pair scoped by your identifier'), clearly indicating the tool's function. It distinguishes itself from sibling tools by explicitly mentioning recall and forget as complementary operations, making it a clear and distinct purpose.

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 ('Use when you discover something worth carrying forward') and gives concrete examples. It also names alternative tools for related actions ('Pair with recall to retrieve later, forget to delete'), offering clear usage context and exclusions.

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