The user wants me to retrieve contribution_rate. I need to:
1. List documents to find the case inputs
2. Read the document to find the payroll month
3. Look up the reference (but which half? I need to know the payroll month first)
4. Return the R8 JSON answer with decision, field, value, clauses

Let me start by listing documents.

The payroll month is 2026-08, which is in the second half of the year (months 7-12 presumably). Let me look up the second-half reference.

The payroll month 2026-08 falls within the second-half row (2026-07 through 2026-12). The contribution_rate is 0.05.

For a retrieval task, I return:
- decision: "retrieve"
- field: "contribution_rate"
- value: "0.05" (decimal string, not percentage)
- clauses: R1 (selecting rule) and R3 (source rule), not R8.

The months field shows ["2026-07", "2026-12"] which likely means the range from 2026-07 to 2026-12. 2026-08 falls in that range.

Value as decimal string: "0.05".

The task is a retrieval task: retrieve contribution_rate for the supplied payroll month. I need to list documents, read them to find the payroll month, then lookup_reference to get the rate.

Let me start by listing documents.

The payroll month is 2026-08, which is the second half of the year. Let me look up the second-half reference.

The payroll month is 2026-08. The second-half reference covers months 2026-07 through 2026-12 (the list shows ["2026-07", "2026-12"], which presumably means July through December). 2026-08 falls in that range. The contribution_rate is "0.05".

The answer: decision "retrieve", field "contribution_rate", value "0.05", clauses ["R1", "R3"] (R8 is the answer-format rule, not to be cited; cite R1 selecting rule and R3 source rule).

The task is a retrieval task: retrieve `contribution_rate` from the supplied rulebook. I need to:
1. List documents and read them to find the payroll month.
2. Look up the reference for the applicable half.
3. Return decision: "retrieve", field: "contribution_rate", value as decimal string, clauses citing R1 and R3.

Let me start by listing documents and looking up references. Actually, I need the payroll month first from the documents. Let me list documents first, then read them. The lookup_reference calls are independent of the documents? No — I need to know which half to look up based on the payroll month. But I could look up both halves in parallel with listing documents. Actually, to be safe, let me list documents first, then read the document to find the month, then look up the correct reference half.

I can do list_documents and both lookup_reference calls in parallel since they're independent. But the instructions say to only look up the applicable one. Looking up both is fine — but maybe better to just list documents first, then decide. Actually, calling both lookups upfront is harmless and saves a round trip. But the rules say "Reference rows are available only through lookup_reference" — I should use the one covering the payroll month. Let me first list documents and read the document, then lookup the right half.

Let me call list_documents first (alone, since read_document depends on its output).

The payroll month is 2026-08, which is in the second half of 2026. I need to look up the second-half reference to get the contribution_rate.

The payroll month is 2026-08, which falls within the second-half reference row (2026-07 through 2026-12). The contribution_rate is "0.05".

This is a retrieval task. Return:
- decision: "retrieve"
- field: "contribution_rate"
- value: "0.05"
- clauses: R1 and R3 (cite the selecting rule R1 and the source rule R3, not R8).

Value is a decimal string, not a percentage. So "0.05".