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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds valuable context beyond annotations by disclosing scoping to the caller's identifier (anonymous IP, BYO key hash, or account ID) and the listing behavior when the key is omitted. 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 three tightly constructed sentences, each earning its place: functionality, usage context, and scoping/complementary tools. It is front-loaded with the primary verb and resource, with zero waste.

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 one-parameter retrieval tool with strong annotations, the description covers behavior, parameter semantics, scoping, and relationship to siblings. No additional return-value documentation is needed given the clarity of 'retrieve a value' and 'list all saved keys'.

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 coverage is 100% with a clear parameter description. The tool description adds further meaning by providing concrete examples of keys (ticker, address, research notes) and explains how omitting the key triggers list-all behavior, enriching the bare schema definition.

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 states a specific verb (retrieve/list) and resource (previously saved values), distinguishing it from sibling tools by explicitly naming remember and forget as the complementary operations. The dual behavior (value retrieval vs. listing all keys) is clearly specified.

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 a concrete use case ('look up context the agent stored earlier') and provides explicit alternatives/companions ('Pair with remember to save, forget to delete'). It makes clear when to use this tool versus other memory operations.

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