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

Annotations already declare the tool as read-only, idempotent, and non-destructive. The description adds valuable context beyond that: the scoping mechanism ('anonymous IP, BYO key hash, or account ID') and the dual-mode behavior of omitting the key to list all keys. This enriches the behavioral picture without contradicting 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 sentences long, with the primary action front-loaded. Every sentence adds value: the action, the use case, and the scoping/pairing context. No filler or redundancy.

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 (one optional parameter, clear annotations, no output schema), the description covers all essential aspects: what it does, when to use it, how the key parameter behaves, and how scoping works. It is fully self-contained for an agent to select and invoke the tool 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 coverage is 100% and the parameter description already explains the key. The description adds semantic context by linking the key to values saved via 'remember' and giving concrete examples (user's target ticker, address, research notes). This clarifies the nature of the stored values beyond the schema's generic description.

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 specific actions: 'Retrieve a value previously saved via remember, or list all saved keys'. It uses a specific verb ('Retrieve') and resource ('value previously saved'), and distinguishes itself from sibling tools by explicitly pairing with 'remember' and 'forget'.

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 clear context on when to use: 'Use to look up context the agent stored earlier… without re-deriving it from scratch' and mentions scoping. It implicitly distinguishes from alternatives by naming 'remember' and 'forget' as complementary tools, but doesn't explicitly say when *not* to use it.

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