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.
npx agentmods add instructions/sbroenne/mcp-server-excel/testing-strategygit clone --depth 1 https://github.com/sbroenne/mcp-server-excelWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00620 | $0.00620 |
| Opus 5 | $0.00310 | $0.00310 |
| Sonnet 5 | $0.00124 | $0.00124 |
| Haiku 4.5 | $0.00062 | $0.00062 |
Grade A, and why
mcp-server-excel testing-strategy.instructions.md 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 3d ago.
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.
How it starts
The opening of the file, as written. The whole thing — 71 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Testing strategy
Use the narrowest existing project and filter that cover the change. Set an explicit timeout in the terminal/tool invocation for every Excel-dependent run.
Commands
# One Core feature
dotnet test tests\ExcelMcp.Core.Tests\ExcelMcp.Core.Tests.csproj --filter "Feature=PowerQuery&RunType!=OnDemand"
# One MCP tool
dotnet test tests\ExcelMcp.McpServer.Tests\ExcelMcp.McpServer.Tests.csproj --filter "FullyQualifiedName~PowerQuery"
# One CLI command group
dotnet test tests\ExcelMcp.CLI.Tests\ExcelMcp.CLI.Tests.csproj --filter "FullyQualifiedName~PowerQuery"
# Session and batch infrastructure
dotnet test tests\ExcelMcp.ComInterop.Tests\ExcelMcp.ComInterop.Tests.csproj --filter "RunType=OnDemand"
# One named test while debugging
dotnet test tests\ExcelMcp.Core.Tests\ExcelMcp.Core.Tests.csproj --filter "FullyQualifiedName=Namespace.Class.Method"
VBA tests require Excel Trust Center access. Screenshot tests run separately because they use desktop/clipboard resources.
Test design
- COM-dependent behavior uses real Excel integration tests. Do not mock
IExcelBatchor Excel COM to claim interop coverage. - Pure parser, mapper, generator, and serialization behavior may use fast non-COM tests when no Excel behavior is involved.
- A regression test must fail for the missing behavior before the implementation changes and pass afterward.
- Verify the resulting workbook state and all relevant result fields, not only
Success. - Test errors with precise assertions; do not accept multiple incompatible outcomes.
Isolation and fixtures
- Create a unique workbook per test with the established fixture/helper.
- Do not share mutable workbooks between tests.
- Do not combine
IClassFixture<T>with a collection fixture on the same class; that can create competing Excel sessions. - Use
.xlsmfor VBA scenarios. - Include the repository's required traits (
Category,Feature,Layer,RequiresExcel,Speed, andRunTypewhere applicable) by following nearby tests in the same feature.
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.
- 3d ago First seen · 71 lines · 620 tokens per session scan A 8018a12c8746
mcp-server-excel testing-strategy.instructions.md is an instructions file published in the GitHub repository sbroenne/mcp-server-excel (645 stars, last pushed 3d ago), licensed MIT. It adds 620 tokens to every session, about $0.0031 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 2026-08-30.
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