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

The description adds meaningful details beyond the annotations: memory is scoped by user identifier, authenticated users get persistent memory, anonymous sessions retain data for 24 hours. This goes beyond the readOnlyHint, idempotentHint, and destructiveHint annotations, which are consistent with the tool's write-once/overwrite semantics. No contradiction with 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 four sentences, each earning its place: purpose, use case, storage details, and related tools. It is front-loaded with the core function and free of filler, making it easily parseable.

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 fully covers purpose, when to use, storage behavior, and related tools. It gives the agent everything needed to invoke the tool correctly without extraneous detail.

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 baseline is 3. The description adds value by clarifying 'key-value pair scoped by your identifier' and stating the value can be 'any text — findings, addresses, preferences, notes,' which reinforces the schema's parameter descriptions and adds usage context.

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 'Save data the agent will need to reuse later,' which is a specific verb+resource that clearly states the tool's function. It distinguishes itself from siblings by explicitly naming 'recall' and 'forget' as complementary tools, showing how it fits into the broader toolkit.

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?

It provides clear when-to-use guidance: 'Use when you discover something worth carrying forward... so you don't have to look it up again.' It also names alternatives and complementary tools ('Pair with recall to retrieve later, forget to delete'), giving the agent actionable decision criteria.

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