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ADR 0058: Pairing the agent and Roslyn MCP in settings.toml (limits, node types, timeouts, presets)

Status: Proposed
Date: 2026-04-18

ADR Role
0008 MCP contracts
0028 settings.toml
0039 navigation, MCP presets; UI intent map
0040 TOML pattern
0053 intent map on PFD
0059 profiles, Manager, Auto-Focus/Combat/Echelon modes, EFB on third monitor - separate ADR

Context

The agent layer and Roslyn are connected through MCP tools. Without explicit rules about how much and what to give, the agent overloads the context or underreceives the structure. This needs to be changed in the config (0028), without necessarily editing C#.

Intuition (not the ADR norm): agent layer - request circuit, Roslyn MCP - semantics gateway; The settings below set volume, filter, timing.

Already available (not cancelled):

This ADR is agent ↔ Roslyn MCP pairing parameters layer in TOML. Behavior of profiles, Manager, tactics/strategy, third monitor - 0059.

Solution (principles)

1. One declarative scheme - several consumers

Category Example of meaning Who is obliged to take into account
Response volume limits max_nodes_per_query, traversal depth limits Roslyn MCP (or Graph Aggregation Adapter)
Filter types of nodes/symbols included_kinds / exceptions Roslyn MCP
Timeouts / “dirty” semantics awaiting compilation vs stale graph Roslyn MCP ± IDE
Query Mode Presets conditional ExploreMode / RefactoringMode Roslyn MCP; agent can override in call

Priority rule: call argument > TOML section > server default - commit in implementation and MCP-PROTOCOL.md when fields appear.

2. Four groups of parameters (contract axes)

  1. Throttling & scoping - volume and depth limits per request (max_nodes_per_query, max_recursion_depth or equivalents in the tool specification).

  2. Visibility mapping (capabilities) - what classes of nodes/symbols are in the results.

  3. Timeouts and consistency - wait for compilation; stale graph; time limits for heavy queries.

  4. Instrumental presets - named sets (controlFlow / architecture / overview vs refactoring). Link to 0039: link by name or orthogonal presets - no implicit merge.

3. Posting in TOML

Target section, for example [agent.roslyn_mcp], separate from [semantic_map] and from [[code_navigation.presets]] (0039) without explicit mapping. Exact keys - after the prototype; here the axes are fixed.

4. Versioning

Optional keys and obvious defaults; changing the required form - bump schemas (0028).

5. Minimum v0 vs deferred

v0: limits + one or two timeouts + one “overview vs deeper” preset without full included_kinds.

Postponed: comprehensive directory of kinds, complex recursion, megaconfig; automation of profiles and modes - 0059.

Consequences

  • Explicit PR contract: the key refers to the MCP server or IDE.
  • Tests for defaults and merge priorities.

Rejected alternatives

  • Only env - worse reproducibility.
  • Only a system prompt - there is no determinism at the tool level.

Open questions

  • Synchronization with the standalone roslyn-mcp config outside the IDE - one scheme or two.
  • What tools are in the scope of the first implementation (navigation / semantic map / both).