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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description's behavioral transparency is supplemented. It adds scoping details (tied to identifier) and the listing behavior, but does not disclose additional traits like rate limits or performance. This is adequate given the 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 two sentences, front-loaded with the primary action, and every sentence provides essential information without redundancy. It is efficiently structured for quick comprehension.

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 retrieval tool with one optional parameter and no output schema, the description covers the core behavior, scoping, and relationship to siblings. It is complete enough for the tool's complexity, though it could optionally mention return format; not necessary but would not harm.

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?

The input schema covers the single parameter 'key' with 100% description coverage. The description enhances this by explaining the listing behavior when omitted and providing concrete examples (user's target ticker, address), adding value beyond the schema's minimal 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 retrieves a previously saved value or lists all saved keys, using specific verb 'Retrieve' and resource 'value previously saved via remember'. It distinguishes from siblings by mentioning 'remember' and 'forget' and provides concrete examples of usage, making the purpose unambiguous.

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 explicitly explains when to use the tool (to look up context stored earlier) and how to list all keys (omit the key argument). It pairs with remember and forget, giving clear context, but does not explicitly state when not to use it or provide alternative tools beyond the siblings mentioned.

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