Missing citation
This page explains what the Missing citation rule checks, what it needs, and how to set its citation marker for your output.
Definition
Missing citation flags a model answer that doesn't include a citation marker. It checks each LLM call (span) that returned output. If the output doesn't match the pattern in Citation marker, the rule fails that call.
Property | Value |
Key |
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Unit |
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Check kind | deterministic |
Category | Output integrity |
Score type |
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Default severity |
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The rule passes a call when its output contains a match for the pattern. It fails the call when the output has no match. LLM calls with empty output aren't checked, and no result is recorded for them.
When the rule fails a call, the reasoning shows the pattern it looked for. For example: "no citation marker matching [(Doc )?\d+]". The result also includes an excerpt of the output.
Why it matters
A grounded answer should tell the user where its facts come from. If your app asks the model to cite its sources and the model stops doing so, the answer may still look fine. This rule catches the missing citation on every call, without a model call of its own, so it adds no model cost.
Use this rule only where citations are required. Every LLM call in the rule's project is checked, so in a project with general chat, the rule flags every chat turn that has no citation.
What it requires
- Traced LLM calls with output. The rule reads the output of each LLM call. To send traces, see Instrument your code.
- Citation markers in your output. Your prompt or app has to produce a marker the pattern can match, such as
[1]or[Doc 2]. - Permission to change rules in the project. For details, see Project permissions.
The rule has one parameter.
Parameter | Required | Default | What it does |
Citation marker | Yes |
| An RE2 regular expression that describes what a citation looks like in your output. |
If you leave Citation marker blank, saving shows "Citation marker is required."
Configuration examples
To add the rule, follow Create a rule. On the New rule page, search for Missing citation or missing_citation, and then select Configure › on its card.
On the Configure rule page, enter a pattern for Citation marker that fits how your app cites sources, and then select Save & enable.
The following table shows patterns for common citation styles.
Your citation style | Citation marker | Counts as a citation |
Numbered, with or without "Doc" (default) |
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Numbered only |
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"Doc" and a number only |
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Tip
Escape the square brackets with \. Without the backslash, the pattern reads [Doc 3] as a set of single characters instead of a literal citation.
Related
- Empty output checks the calls this rule skips, the ones that returned nothing.
- Expected format absent checks that output matches a shape you define, such as a heading or a table.
- Groundedness uses a model to judge whether an answer is supported by the retrieved context.
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