pptx-author skill

pptx-author

Produce a .pptx file on disk using python-pptx. Use when you need to deliver a deck as a file artifact, not drive a live PowerPoint session.

Adapted from Anthropic's pptx-author and pitch-deck skills in anthropics/financial-services. The MCP / Office-JS branches of the originals are dropped — this assumes headless Python.

For the broader, already-shipped PowerPoint authoring skill (slides, speaker notes, embeds, media), see the built-in microsoft-office skill. This skill is a lighter-weight pattern tuned for model-backed decks (pitch decks, IC memos, earnings notes) where every number must trace to a source workbook.

Output contract

• Write to ./out/.pptx. Create ./out/ if it does not exist.
• Return the relative path in your final message.

Setup

Use python when it already imports pptx (the Hermes Docker image ships it). Otherwise, when hermes is on PATH, let Hermes build its shared, pinned documents environment under the Hermes home (safe to run from several agents at once); in a Docker sandbox without Hermes the block builds a venv in the sandbox home with the same pinned versions. It is the same block as the microsoft-office/pdf skills. Never pip install into the interpreter that runs Hermes:

python -c "import pptx" 2>/dev/null && PY=python || if command -v hermes >/dev/null 2>&1; then
  PY="$(hermes pm environment documents --extra documents --extra documents-pdf)"
else
  PY="$HOME/.cache/hermes-docs-venv/bin/python"
  "$PY" -c "import docx, openpyxl, pptx, reportlab, pypdf, pdfplumber, pypdfium2" 2>/dev/null || (
    # Safe to run from several agents at once: each caller builds a private venv,
    # a symlink publishes the first finished one atomically, the others delete theirs;
    # a published build is replaced and deleted only while it still fails to import.
    mkdir -p "$HOME/.cache" && cd "$HOME/.cache" && stage="$(mktemp -d hermes-docs-venv.XXXXXX)" || exit 1
    old="$(readlink hermes-docs-venv)"  # the published build, if any (another agent may have just published it)
    python3 -m venv "$stage" &&
      "$stage/bin/python" -m pip install -q --disable-pip-version-check python-docx==1.2.0 openpyxl==3.1.5 python-pptx==1.0.2 reportlab==5.1.0 pypdf==6.21.4 pdfplumber==0.11.10 pypdfium2==5.14.0 &&
      "$stage/bin/python" -c "import docx, openpyxl, pptx, reportlab, pypdf, pdfplumber, pypdfium2" &&
      if [ -z "$old" ]; then python3 -c 'import os, sys; os.syml

Run the deck-building Python with "$PY".

Core conventions

One idea per slide

Title states the takeaway; body supports it. A slide titled "Q3 Revenue" is weak; "Revenue growth accelerated to 14% Y/Y in Q3" is strong.

Every number traces to the model

If a figure on a slide came from ./out/model.xlsx, footnote the sheet and cell.

Revenue: $1,250M  (Source: model.xlsx, Inputs!C3)

Never transcribe numbers from memory or from a summary — open the workbook, read the named range, and bind the deck value to it programmatically when you can.

Use the firm template when one is mounted

If ./templates/firm-template.pptx exists, load it so the deck inherits branded colors, fonts, and master layouts.

from pptx import Presentation
from pathlib import Path

template = Path("./templates/firm-template.pptx")
prs = Presentation(str(template)) if template.exists() else Presentation()

Charts: PNG-from-model beats native pptx charts

When fidelity matters (the model's chart styling must match the deck exactly), render the chart to PNG from the source workbook and embed the image. Native pptx.chart charts are fragile and often don't match firm conventions.

from pptx.util import Inches
slide.shapes.add_picture("./out/charts/football_field.png",
                         Inches(1), Inches(2),
                         width=Inches(8))

No external sends

This skill writes a file. It never emails, uploads, or posts. Orchestration layers handle delivery.

Skeleton

from pptx import Presentation
from pptx.util import Inches, Pt
from pptx.dml.color import RGBColor
from pathlib import Path

template = Path("./templates/firm-template.pptx")
prs = Presentation(str(template)) if template.exists() else Presentation()

# Title slide
slide = prs.slides.add_slide(prs.slide_layouts[0])
slide.shapes.title.text = "Project Aurora — Strategic Alternatives"
slide.placeholders[1].text = "Preliminary Discussion Materials"

# Valuation summary slide (title-only layout)
slide = prs.slides.add_slide(prs.slide_layouts[5])
slide.shapes.title.text = "Valuation implies $38–$52 per share across methodologies"

# Add a table bound to model outputs
rows, cols = 5, 4
tbl_shape = slide.shapes.add_table(rows, cols,
                                   Inches(0.5), Inches(1.5),
                                   Inches(9), Inches(3))
tbl = tbl_shape.table
headers = ["Methodology", "Low ($)", "Mid ($)", "High ($)"]
for c, h in enumerate(headers):
    tbl.cell(0, c).text = h

# In a real deck, read these from the model workbook with openpyxl
data = [
    ("Trading comps",     "35", "41", "48"),
    ("Precedent M&A",     "39", "45", "52"),
    ("DCF (base)",        "36", "43", "

Binding deck numbers to the source workbook

Read named ranges or specific cells from your Excel model so deck numbers never drift.

from openpyxl import load_workbook

wb = load_workbook("./out/model.xlsx", data_only=True)
def nr(name):
    """Resolve a named range to its current computed value."""
    rng = wb.defined_names[name]
    sheet, coord = next(rng.destinations)
    return wb[sheet][coord].value

revenue_fy24 = nr("RevenueFY24")
implied_mid  = nr("ImpliedSharePriceBase")

Then build deck content using those values:

slide.shapes.title.text = f"Implied share price of ${implied_mid:.2f} (base case)"

Remember to recalculate the workbook before reading it — openpyxl only sees computed values if something has already calculated the sheet. Run the recalc helper in the excel-author skill first, or open/save through a real Excel session.

Slide-type checklist for pitch decks

A typical banking pitch deck follows this structure. Not prescriptive, but useful as a starting skeleton:

1. Cover / title
2. Disclaimer
3. Table of contents
4. Situation overview
5. Company snapshot (the target)
6. Market / sector context
7. Valuation summary (football field) — the money slide
8. Trading comps detail
9. Precedent transactions detail
10. DCF summary
11. Illustrative LBO / sponsor case
12. Process considerations

When NOT to use this skill

• Users in a live PowerPoint session with an Office MCP available — drive their live doc instead.
• Non-financial slideware (quarterly all-hands, marketing decks) — use the broader microsoft-office skill.
• Decks with heavy animation, transitions, or speaker notes — use the broader microsoft-office skill.

Attribution

Conventions adapted from Anthropic's Claude for Financial Services plugin suite, Apache-2.0 licensed. Original: https://github.com/anthropics/financial-services/tree/main/plugins/agent-plugins/pitch-agent/skills/pptx-author