Remember a fact

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

Since annotations only state readOnlyHint=false and idempotentHint=false, the description adds critical behavioral context by disclosing that writing an existing key appends a new version rather than overwriting, ensuring no data loss. It also implies that the tool mutates state (non-read-only) consistent with annotations. It does not mention potential side effects like storage limits or the need for specific permissions, but the key versioning behavior is well covered.

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 a single, clear sentence that is front-loaded with the purpose ('Store a fact') and then efficiently conveys the critical behavioral nuance about versioning. No wasted words, ideal length for an agent to parse quickly.

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?

The tool has 5 parameters, 2 required, and no output schema, so the description needs to cover mutation behavior and parameter usage. It does so adequately by explaining the versioning behavior and clarifying the scope+key structure. However, it does not specify return values or any potential errors, but with no output schema and high schema coverage, the description is reasonably complete for an agent to invoke 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?

The schema has 100% coverage, with descriptions for all parameters (e.g., 'Name inside the scope' for key, 'Labels for later filtering' for tags). The description adds meaning by framing the parameters as 'scope+key' and explaining that value can be any JSON, but it does not go beyond schema for individual parameters. Since schema coverage is high, the baseline is 3, but the description's emphasis on the scope+key pairing and the versioning behavior adds practical semantics that elevate it slightly.

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 'Store a fact under scope+key', using a specific verb (store) and resource (fact with scope and key). It distinguishes from siblings like 'recall' (which presumably retrieves) and 'history' (which shows versions). The mention of versioning behavior further differentiates it from a simple write operation.

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 explains when to use this tool (to store facts) and implicitly when not (it appends rather than overwrites, so users must be aware). It does not explicitly name alternative tools like 'recall' for retrieval, but the context signals include sibling tools that suggest the use case. The versioning guideline helps clarify a key decision point for the agent.

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