MCP Observatory

Instructions

Implementation Reference

• src/server.ts:127-168 (handler)

  The MCP tool 'get_last_run' is registered and implemented directly within src/server.ts. It processes the request, locates the relevant artifact file, and returns its content.

  server.tool(
    "get_last_run",
    "Return the most recent run artifact for a given target ID. Searches the default runs directory.",
    {
      targetId: z.string().describe("The target ID to find the last run for (e.g. server name or command)."),
      runsDir: z.string().optional().describe("Custom runs directory. Defaults to .mcp-observatory/runs in cwd."),
    },
    async ({ targetId, runsDir }) => {
      try {
        const dir = runsDir ?? defaultRunsDirectory();
        let files: string[];
        try {
          files = await readdir(dir);
        } catch {
          return { content: [{ type: "text" as const, text: `No runs directory found at ${dir}` }], isError: true };
        }
  
        // Filter to JSON files matching the target, sorted newest-first by filename (ISO timestamp prefix)
        const needle = targetId.toLowerCase();
        const matching = files
          .filter((f) => f.endsWith(".json") && f.toLowerCase().includes(needle))
          .sort()
          .reverse();
  
        if (matching.length === 0) {
          return { content: [{ type: "text" as const, text: `No run artifacts found for target "${targetId}" in ${dir}` }] };
        }
  
        const latest = matching[0]!;
        const artifact = await readArtifact(path.join(dir, latest));
        if (artifact.artifactType !== "run") {
          return { content: [{ type: "text" as const, text: `Latest matching file is not a run artifact: ${latest}` }], isError: true };
        }
  
        return {
          content: [{ type: "text" as const, text: `${formatRun(artifact)}\n\nFile: ${path.join(dir, latest)}` }],
        };
      } catch (error) {
        const msg = error instanceof Error ? error.message : String(error);
        return { content: [{ type: "text" as const, text: `Error reading last run: ${msg}` }], isError: true };
      }
    },