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

Annotations already signal nontrivial behavior (readOnlyHint=false, idempotentHint=true, destructiveHint=false), so the bar is lower. The description adds valuable context beyond annotations: storage mechanism ('key-value pair scoped by your identifier') and persistence duration (authenticated vs anonymous sessions). This is meaningful but not exhaustive (e.g., no mention of overwriting behavior beyond idempotency).

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?

Four sentences, each carrying distinct information: purpose, when to use, storage mechanics, and pairings. No redundancy, no filler. The front-loaded verb 'Save' immediately communicates action.

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 write tool with no output schema, the description is fully adequate. It covers what the tool does, when to use it, persistence behavior, and how it relates to recall and forget. No critical gaps remain 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%: both parameters (key, value) are already documented with types and examples. The description adds marginal value by framing them as a key-value pair and noting the identifier scoping, but it doesn't meaningfully extend the schema's clarity. Baseline 3 applies because 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 opens with a specific verb and resource: 'Save data the agent will need to reuse later.' It clearly differentiates from siblings by naming recall and forget as complementary tools, and the scope ('across this conversation or across sessions') adds precision.

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 explicitly states when to use the tool: 'Use when you discover something worth carrying forward...' and provides alternatives: 'Pair with recall to retrieve later, forget to delete.' This gives the agent clear decision criteria.

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