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Erstan content is split into deterministic operations and reusable guidance. Use the narrowest object that fits the job.

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Layers

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Decision Tests

  • Tool: you would write an automated test asserting its output.
  • Skill: you would review its output like a colleague’s work.
  • Agent: who is doing the work.
  • Template: you copy and edit it.
Deterministic operations are tools. Behavioral guidance is a skill. Identity and composition are agents. Anything intended to be copied and edited is a template.

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Skill Tiers

T1 built-in skills may reference only Runtime Baseline tools. Broader or domain-specific tool use belongs in T2 curated skills and agents.

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Tool Prefixes

  • er_ tools are Erstan-native deterministic operations.
  • ns_ tools are NetSuite MCP core tools.
  • er_ns_ tools are Erstan SuiteApp custom NetSuite MCP tools.
  • er_suiteql_example_find, er_suiteql_query_validate, and er_suiteql_query_fix are Erstan-native SuiteQL helpers. Their former ns_ names are accepted only as backward-compatible runtime aliases.

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Worked Example

Use er_file_load to read or OCR a file. Use the File Understanding skill when the task needs interpretation, classification, comparison, or schema-shaped extraction after loading the file. The tool gives the model reliable bytes and text. The skill teaches when and how to reason over that material.