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

Annotations already mark this as idempotent and non-destructive. The description adds valuable context: memory is scoped by agent identifier, authenticated users get persistent memory, anonymous sessions retain for 24 hours, and data is stored as a key-value pair. This complements the annotations without contradicting them.

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 total: purpose, usage guidance, and persistence/companion tools. Each sentence earns its place, and the most important information is front-loaded. No filler or redundancy.

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 no output schema, the description covers the essential aspects: what to store, when to use it, scope, persistence, and how to retrieve/delete. The annotations cover the safety profile, and the description fills in the operational details completely.

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 examples, and coverage is 100%, so baseline is 3. The description adds semantic context by listing typical key categories (resolved ticker, target address, user preference) and clarifying that value can be 'any text — findings, addresses, preferences, notes,' which goes beyond the schema by conveying intent.

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 opens with the specific verb 'Save' and clearly identifies the resource: 'data the agent will need to reuse later.' It also distinguishes from siblings by explicitly pairing with recall and forget, making the tool's role in the memory workflow unambiguous.

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 gives concrete when-to-use guidance: 'Use when you discover something worth carrying forward,' with examples like 'a resolved ticker, a target address, a user preference, a research subject.' It names alternative tools (recall/forget) but does not explicitly state when not to use this tool, so it stops short of a full 5.

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