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

Adds behavioral context beyond annotations, including persistence differences (authenticated persistent vs. anonymous 24-hour retention), scoping by identifier, and the key-value storage model. Does not contradict the readOnlyHint=false or idempotentHint=true 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?

The description is compact but comprehensive, front-loading the primary purpose and including all necessary usage context. Every sentence contributes value, with no redundancy or filler.

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 a full schema and useful annotations, the description covers usage scenarios, persistence behavior, and sibling relationships. No output schema is needed, and the description is complete for effective tool selection and 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%, providing clear descriptions for key and value. The description adds semantic nuance by explaining that keys are scoped by identifier and offering example keys and value types, enriching the meaning beyond the schema alone.

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 function with a specific verb ('save') and resource ('data the agent will need to reuse later'). It distinguishes itself from siblings by mentioning cross-session persistence and key-value scoping, and explicitly contrasts with recall and forget.

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 with concrete examples (resolved ticker, target address, user preference, research subject). It also states the relationship to recall and forget, giving clear context for when this tool is the right choice.

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