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

Annotations cover idempotency and non-destructiveness, but the description adds valuable behavioral context: 'scoped by your identifier' and persistence details ('Authenticated users get persistent memory; anonymous sessions retain memory for 24 hours'). This goes beyond what annotations express, clarifying how the memory behaves across sessions.

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 five sentences, each earning its place: purpose, usage examples, storage mechanics, persistence behavior, and companion tools. It is front-loaded with the primary action and contains no filler or repetition.

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 covers all necessary ground: what it stores, when to use it, how data is scoped, retention policy, and related tools. Nothing critical is missing for an agent to invoke it 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%, with both 'key' and 'value' already described with examples. The description adds no new parameter-specific semantics beyond calling it a 'key-value pair', which is already implicit in the schema. Baseline of 3 is appropriate since the 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?

The description clearly states the tool's action ('Save data the agent will need to reuse later') with a specific resource (key-value memory). It also distinguishes itself from siblings by explicitly mentioning 'Pair with recall to retrieve later, forget to delete', which differentiates it from the related tools.

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 when-to-use guidance with concrete examples ('a resolved ticker, a target address, a user preference, a research subject') and names the companion tools (recall, forget) as alternatives/complements. This leaves no ambiguity about appropriate invocation.

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