fill-form

fill-form is a command for coding agents from anthropics/knowledge-work-plugins. It costs 10 tokens per session (805 once invoked), scanned A, original, Apache-2.0.

Fill PDF form fields interactively with live visual feedback.

Command

About the project

Knowledge Work Plugins is an open-source collection of Claude extensions organized around roles such as productivity, sales, and customer support. Each plugin combines role-specific guidance, connectors, commands, and sub-agents so knowledge workers can use Claude with their team’s tools and processes. The catalogue entries are examples of, or workflows from, this plugin collection.

anthropics/knowledge-work-plugins · 23,877 stars · on GitHub

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/anthropics/knowledge-work-plugins/fill-form
Clone the repo
git clone --depth 1 https://github.com/anthropics/knowledge-work-plugins

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for fill-form

README.md
[![agentmods](https://agentmods.dev/badge/commands/anthropics/knowledge-work-plugins/fill-form.svg)](https://agentmods.dev/commands/anthropics/knowledge-work-plugins/fill-form)
Your own site
<a href="https://agentmods.dev/commands/anthropics/knowledge-work-plugins/fill-form"><img src="https://agentmods.dev/badge/commands/anthropics/knowledge-work-plugins/fill-form.svg" alt="Measured on agentmods" height="20"></a>
Per session 10 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 805 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00010 $0.00805
Opus 5 $0.00005 $0.00402
Sonnet 5 $0.00002 $0.00161
Haiku 4.5 $0.00001 $0.00081

Measured today against content hash 787ca13d2032, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fill-form scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

pdf-viewer/commands/fill-form.md · 74 lines

How it starts

The opening of the file, as written. The whole thing — 74 lines — stays where its author put it; the contents beside it link to each section on GitHub.

If you need to check which tools are connected, see CONNECTORS.md.

Fill Form

Help the user complete a fillable PDF form in the live viewer. Unlike programmatic form tools, this gives the user direct visual feedback on every field as it's filled, with easy undo/edit in the viewer.

Why use this instead of programmatic form filling

  • Visual confirmation — the user sees each value land in the right box, not just a success message
  • Unnamed/unlabeled fields — many real-world PDFs have fields with machine names like Text1, Field_7, or no name at all. The label ("Date of Birth", "SSN") is printed next to the field on the rendered page, not in the field metadata. Use get_screenshot to see what each field actually is, then fill by name.
  • Easy correction — the user can edit or clear any field directly in the viewer, or ask you to fill_form again with new values

Two approaches

User-driven (simple, well-labeled forms)

Call display_pdf with elicit_form_inputs: true. The server detects form fields and prompts the user to enter values before the viewer opens. The filled PDF is then displayed.

AI-assisted (complex forms, unnamed fields, or when you have context)

  1. display_pdf (without elicit) — inspect returned formFields (name, type, page, bounding box)
  2. If field names are cryptic (Text1, Field_7), use interactget_screenshot of each page with fields. Look at the visual labels next to each bounding box to understand what each field is.
  3. For each field, either:
    • Infer the value from conversation context (name, date, email)
    • Ask the user, describing the field by its visual label ("the 'Date of Birth' box on page 1")
  4. interactfill_form with fields: [{name, value}, ...]
  5. interactget_screenshot of each filled page
  6. Show the user, ask them to confirm or edit

Example

User: Help me fill out this W-9

You: display_pdf → formFields: f1_1, f1_2, f1_3, c1_1, ... (cryptic names)

You: interactget_screenshot page 1 → see f1_1 is next to "Name", f1_2 is "Business name", c1_1 is the "Individual" checkbox

You: "I can see Name, Business name, Address, TIN, and tax classification checkboxes. I'll fill Name and Date from what I know — what's your TIN and business address?"

After answers: interactfill_form + get_screenshot

You: "Here's the filled form [screenshot]. The signature line is still blank — want to add your signature with /pdf-viewer:sign?"

Read the full file on GitHub · 74 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. today First seen · 74 lines · 10 tokens per session scan A 787ca13d2032

Subscribe to this mod's changes

fill-form is a command published in the GitHub repository anthropics/knowledge-work-plugins (23,877 stars, last pushed today), licensed Apache-2.0. It adds 10 tokens to every session and 805 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-05.