The automation ladder · Choosing a rung

What the agent version costs

Price an agent version of the weekly client report turn by turn, add the review it forces, and decide against the one-call workflow.

estimatehardExercise · 3 min · 18 of 75

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A vendor's demo of the weekly client report, built as an agent, looked better than the workflow being built. The question is what the better-looking version costs a month, all lines included.

The situation

The agency sends 12 client reports a week, each 45 minutes of an account manager's time from six dashboards. The rung 2 workflow fetches all six in code and makes one model call per report: in, a 1,200-token prompt, 6 × 1,000 tokens of figures and 300 of last week's summary; out, 400 tokens.

The vendor's agent has the same prompt and summary plus seven tools, one per dashboard and write_report, whose schemas are 900 tokens. In a shadow week its typical run was 8 turns: six dashboard reads, each adding a 50-token call and a 1,000-token result to the transcript; one write_report turn that outputs 450 tokens and adds 500; then a 50-token confirmation. Every other turn outputs 50. In 2 of 12 shadow runs it read only five dashboards.

Assume the large model at $2 per million input tokens and $8 per million output, 4.33 weeks a month, staff at $30 an hour, 4 extra minutes per report to check which sources it used, and $200 of credibility lost on a report sent missing a source.

The question

Estimate what the agent version costs a month against the workflow, every line included, and decide which to run.

A strong answer · Rubric · Where answers go wrong

Write your answer first, then open

A strong answer

Workflow, per report: 7,500 in × $2 per million = $0.015; 400 out × $8 per million = $0.0032. About $0.018.

Agent, per report. Turn 1 sends 1,200 + 900 + 300 = 2,400. Each read adds 1,050, so turn n of the first seven sends 2,400 + 1,050 × (n − 1):

turns 1–7   7 × 2,400 + 1,050 × (0 + 1 + … + 6) = 16,800 + 22,050 = 38,850
turn 8      2,400 + 6 × 1,050 + 500             =  9,200
input                                             48,050 × $2 per million = $0.096
output      6 × 50 + 450 + 50 = 800                       × $8 per million = $0.0064
per report                                                                 ≈ $0.1025

The transcript term, 22,050, is larger than the prefix term: the dashboard results are resent on every later turn. That is about 5.6 times the workflow.

Per month: 12 × 4.33 = 52 reports. Tokens: 52 × $0.1025 = $5.33 against $0.95, $4.38 more. Review: 52 × 4 minutes = 3.5 hours, $104. Without that check, one run in six skips a dashboard, about 9 reports a month sent short, each risking $200 of credibility. The check is the cheaper line, so it stays.

The agent costs about $108 a month more for nothing the task uses: the six reads never change order, so they are fixed steps, which scripts, workflows and agents already concluded. Run the workflow. Reverse this only if clients need different sources each week, so that a fixed fetch list misses what matters.

Rubric

prices the workflow call and the agent run separately, input and output each
sums the agent's input turn by turn and shows the transcript term outweighing the prefix
converts to a month with 4.33 weeks and states the difference in dollars
adds the review line and the skipped-dashboard risk, not tokens alone
decides, and names the evidence that would reverse it

Where answers go wrong

"Eight turns at 2,400 tokens is 19,200 in, about $0.04 a report." It ignores that every turn resends the transcript; the resent dashboard reads alone are 28,350 of the 48,050 input tokens. Rung 4 and the harness prices a run the same way.

"The tokens are $4 a month more, so take the better demo." The token line is the smallest on the bill. The source check is $104 a month, and dropping it sends about 9 short reports a month.

"Tell the agent in its prompt to always read all six." A rule that must hold every time belongs in code, and if all six are always read, they are fixed steps: the task is the workflow.