facts_at_time

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

The description notes that facts already superseded are excluded, which is a key behavioral trait. With no annotations, it carries the full burden, but it doesn't disclose sorting, pagination, performance, or edge cases. Output schema exists, reducing the need to describe return structure.

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 brief, well-organized with a clear purpose then usage section. Every sentence adds value, and it is front-loaded with the core action.

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 complexity (5 parameters, many siblings, no annotations, output schema exists), the description covers core behavior and usage but misses parameter details for direction/limit and doesn't differentiate from all related tools. Adequate but with gaps.

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 description coverage is 0%, so the description should compensate. It explains 'at', 'entity', and 'predicate' but omits 'direction' and 'limit'. Only 3 of 5 parameters are semantically described, leaving gaps.

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 lists facts about an entity valid at a point in time, using specific verb and resource. However, it does not explicitly differentiate from sibling tools like list_facts or fact_supersession_chain, which also deal with facts.

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 'USE THIS WHEN' section provides explicit scenarios (audit, debugging, historical questions) and a concrete example. It does not mention when not to use the tool or list alternative tools, so it lacks exclusions.

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