file_facts

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

Annotations already declare readOnlyHint and idempotentHint. The description adds value by explaining it computes a file subject fingerprint and returns facts across overlays, providing behavioral context beyond the annotations. No contradictions.

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?

Two sentences, front-loaded with purpose, no wasted words. Perfectly concise.

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?

An output schema exists, so return values need not be explained. However, with 8 parameters and no parameter descriptions in either schema or description, the tool is incomplete for proper use. The description covers purpose and behavior but omits essential parameter guidance.

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 description provides no parameter details despite having 8 parameters with 0% schema description coverage. It mentions 'overlays' but does not explain the overlay parameter or any other required/optional parameters, forcing reliance on the bare schema.

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 it is a read tool for one file's durable facts, computes a file subject fingerprint, and returns specific facts like working_tree_overlay file_snapshot rows. It is specific about verb and resource, but does not differentiate from sibling tools like file_findings or file_health.

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 says 'Use this to inspect what Reef currently knows about a file across overlays,' providing clear context for usage. However, it does not discuss when not to use this tool or mention alternatives among the many sibling tools.

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