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Skills extend Theo with specialized capabilities — domain knowledge, custom tools, prompt extensions, and model preferences. You can activate skills on any completion request by passing their slug.

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Finding a Skill Slug

Every skill has a unique slug (e.g., customer-support, code-review, deep-research). In the Dashboard:
  1. Go to Skills → Marketplace or My Skills.
  2. Each skill card displays its slug — click the copy icon to copy it.
Via API: 
# List all marketplace skills
curl -H "Authorization: Bearer $THEO_API_KEY" \
  https://hitheo.ai/api/v1/skills

# List your installed skills
curl -H "Authorization: Bearer $THEO_API_KEY" \
  "https://hitheo.ai/api/v1/skills?filter=installed"
Both return a skills array. Each object includes slug, name, description, and category. In the E.V.I. Canvas: When you open the Input node with API Call trigger, the canvas shows the skill’s slug with a Copy button. If the canvas hasn’t been published yet, it shows the draft slug preview.

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Using Skills in a Completion

Pass one or more slugs in the skills array: 
curl -X POST https://hitheo.ai/api/v1/completions \
  -H "Authorization: Bearer $THEO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "Summarize recent support tickets for this customer",
    "skills": ["customer-support"]
  }'

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How It Works

When you pass skills:
  1. Slug resolution — Theo looks up each slug and loads the skill’s manifest (prompt extension, tools, model preference).
  2. Merge with installed skills — The requested skills are merged with any skills you already have installed and enabled.
  3. Prompt injection — Each active skill’s system prompt extension is injected into the request context, ordered by priority and intensity.
  4. Tool aggregation — Tools declared by active skills become available to the agent loop.
  5. Model preference — If a skill specifies a preferred model (e.g., theo-1-reason for deep analysis), Theo may route to that model.

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Multiple Skills

You can activate multiple skills simultaneously: 
{
  "prompt": "Extract data from the attached ACORD 125 form and run a compliance check",
  "skills": ["data-extraction", "insurance-compliance"]
}
Skills are applied in the order listed. If skills have conflicting model preferences, the first skill’s preference takes precedence.

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Skills You Don’t Have Installed

You can pass the slug of any public skill in the skills array — you don’t need to install it first. Installing a skill means it’s automatically included in every request; passing it in skills activates it for a single request.

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Building Your Own Skill

See Build with the E.V.I. Canvas to create skills visually, or use the SDK: 
import { defineSkill } from "@hitheo/sdk";

export default defineSkill({
  name: "my-custom-skill",
  tools: [myTool],
  knowledge: ["./docs/*.md"],
});

// Publish: npx theo publish
After publishing, your skill’s slug is available for use in skills arrays immediately.