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

Adds behavioral context beyond annotations: memory is scoped by identifier, persistence differs for authenticated users (persistent) vs anonymous (24 hours). Annotations already declare idempotentHint=true, destructiveHint=false, and the description does not contradict them. It does not mention overwrite behavior for duplicate keys, but the idempotency hint partially covers repeated calls. Overall, good transparency for a simple key-value store.

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 three well-structured sentences, front-loaded with the primary action. Every sentence adds value: first defines what it does, second gives when to use, third explains scoping/persistence and pairs with related tools. No wasteful 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?

Given the tool's simplicity (2 string parameters, no output schema) and the richness of annotations (idempotent, non-destructive), the description fully covers usage context, persistence behavior, and relationship to sibling tools. There is no gap in information that would prevent correct 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?

Input schema has 100% coverage with descriptions for both key and value. The description adds practical examples for the key format ('subject_property', 'target_ticker', 'user_preference') and clarifies the value as 'any text — findings, addresses, preferences, notes.' This enriches the schema but is not strictly necessary given the schema already defines the parameters well.

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: 'Save data the agent will need to reuse later — across this conversation or across sessions.' It names the verb (save), the resource (data), and the scope (across conversations/sessions). It also distinguishes from siblings by mentioning paired tools recall and forget, making the purpose 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?

Provides explicit when-to-use guidance: 'Use when you discover something worth carrying forward (a resolved ticker, a target address, a user preference, a research subject).' It also names alternatives for complementary operations: 'Pair with recall to retrieve later, forget to delete.' This clearly instructs the agent on when to invoke this tool and when to use related tools.

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