Agent Skills¶
The small CLI discovery skill tells agents how to launch the installed plugin for ordinary workbook requests. The optional formatting skills supply presentation conventions for requested reports, not general command catalogs. Native CLI help and MCP tool schemas remain the source for actions, parameters, defaults, and safety.
| Skill | Entry point | Distribution |
|---|---|---|
excel-cli | Plugin's argument-safe npx launcher | excel-cli plugin, skill ZIP (requires the plugin launcher) |
excel-cli-report-formatting | excelcli | excel-cli plugin, standalone skill ZIP |
excel-mcp-report-formatting | Excel MCP tools | excel-mcp plugin, VS Code extension, standalone skill ZIP |
The MCPB configures the server; it does not install agent skills. General workflows, limitations, and recovery guidance live in the documentation reference, not in every skill package. All optional report-formatting conventions remain available, including financial-model colours and dashboard layout.
Why the scope changed¶
The completed real-world comparison used public pytest-skill-engineering 1.0.3 and gpt-6.1-sol. All 48 matched cases passed independent workbook checks. The broad skill was read in all 24 treatment cases, but recorded token usage was 23.4% higher for MCP and 72.4% higher for CLI. Two interrupted attempts had unknown usage and are excluded from those percentages, not treated as free. See the evidence and limitations.
This supports removing broad automatic loading for the tested tasks/model. It does not establish that agents can discover the CLI launcher from a plugin that contains only a formatting skill. A small excel-cli discovery skill restores that entry point without restoring the broad command/reference corpus. It does not prove that the new formatting skills improve agent performance. Their actual selection and value require a separate comparison.
Installation and migration¶
Plugin names remain excel-mcp and excel-cli. They are listed in Awesome Copilot, the default marketplace in current Copilot clients:
Alternatively, install from our direct marketplace:
copilot plugin marketplace add sbroenne/mcp-server-excel-plugins
copilot plugin install excel-mcp@mcp-server-excel-plugins
copilot plugin install excel-cli@mcp-server-excel-plugins
Choose one marketplace per plugin, not both copies of the same plugin. Existing direct-marketplace installations can stay in place.
The same plugin repository is also a Claude Code marketplace:
claude plugin marketplace add sbroenne/mcp-server-excel-plugins
claude plugin install excel-mcp@mcp-server-excel-plugins
claude plugin install excel-cli@mcp-server-excel-plugins
After the release containing this change is published, direct skill installation uses the new identities:
npx skills add sbroenne/mcp-server-excel-plugins --skill excel-cli-report-formatting
npx skills add sbroenne/mcp-server-excel-plugins --skill excel-mcp-report-formatting
The VS Code extension registers only excel-mcp-report-formatting. The source repository contains the three actual skill directories; the prepared release packages add the formatting skills' entry-point-specific reference. Use a complete prepared package when installing manually.
Existing standalone skill installations are not automatically updated or removed. Replace the former broad excel-cli skill with the small discovery skill when updating the CLI plugin. Remove the retired broad excel-mcp skill using your client's skill manager; MCP discovery comes from the server configuration. Do not remove the plugins or their MCP/CLI launch configuration merely because the skill identities changed. Local source edits do not update installed copies or publish new packages.
Authoring and packaging¶
| Content | Canonical source |
|---|---|
| Skill selection and short entry instructions | skills/<skill-name>/SKILL.md |
| Full optional formatting conventions | docs/reference/report-formatting.md |
| General workflows and recovery | docs/reference/*.md |
| Installation and authoring instructions | docs/AGENT-SKILLS.md |
| Tool descriptions and schema metadata | Core interface XML docs/attributes |
| Minimal MCP server instructions | src/ExcelMcp.McpServer/Program.cs |
skills contains actual skills only. Do not add a general documentation corpus, copied command catalog, or another broad entry skill. Keep excel-cli limited to discovery of the plugin's npx wrapper and native help; it carries no references.
Preparation writes complete skills to artifacts\generated-skills. Build-AgentSkills.ps1 copies CLI discovery without references. For the formatting skills it selects only report-formatting.md, renders its matching cli or mcp fenced examples, and links supporting topics to the website. The ZIP, plugins, and extension consume the same prepared output. Ordinary M, DAX, JSON, and other language fences are preserved; no flag translation occurs.
Do not edit generated, packaged, installed, or published copies. Validate both formatting skill directories and the CLI discovery skill with the public loader before paid tests. Availability is not evidence of loading, and loading is not evidence of benefit. Keep unrelated reads, raw exports, data edits, refreshes, and recovery outside the formatting trigger. Preserve user/template precedence and all optional conventions. See evaluation authoring.