| name | fact-check-before-trust |
| version | 1.0 |
| category | core |
| description | Triggers a secondary verification pass for any agent output containing factual claims, numbers, dates, or named entities before the output is acted on |
fact-check-before-trust
verification-before-completion checks that a task was done. This skill checks that the facts are correct. An agent confidently reporting a £716 visa fee as £70,000 will pass completion verification — this skill catches it.
When to invoke
Invoke this skill before treating any agent output as authoritative when the output contains:
- Numbers or money (prices, quantities, measurements, statistics)
- Dates and deadlines (filing deadlines, release dates, expiry dates)
- Named entities (people, organisations, laws, product names)
- Causal claims ("X causes Y", "because of Z")
- Superlatives ("the largest", "the only", "the most recent")
Skip for: code output, file system operations, and clearly self-contained tasks (renaming a variable, formatting a document).
Verification protocol
Step 1 — Extract claims
Identify every verifiable claim in the output. List them explicitly:
Claim 1: UK visa fee is £716
Claim 2: Processing time is 3 weeks
Claim 3: Applies to Tier 2 (Skilled Worker) visa category
Step 2 — Score each claim
For each claim, assign a confidence level:
- High — Agent has direct evidence in its context (read a document, fetched a URL)
- Medium — Agent inferred from training data (check recency)
- Low — Agent stated without citing a source
Step 3 — Verify low/medium claims
For each Low or Medium claim:
- Search or re-fetch the source if possible
- If source found: update confidence to High or mark Contradicted
- If no source available: mark Unverifiable
Step 4 — Classify output
| Result | Meaning |
|---|
| ✓ Verified | All claims High confidence |
| ⚠ Uncertain | 1+ Unverifiable claims |
| ✗ Contradicted | 1+ claims conflict with found evidence |
Step 5 — Surface to user
- Verified: proceed
- Uncertain: surface unverifiable claims with a note
- Contradicted: stop, show the contradiction, do not use the output until resolved
Difference from verification-before-completion
verification-before-completion checks: "Did the agent do the task?" (task completion)
fact-check-before-trust checks: "Is what the agent said true?" (output accuracy)
Both should be used for research, financial, legal, and compliance workflows.
