Pub.dev MCP Server

Instructions

Implementation Reference

• src/pubdev-mcp.js:354-391 (handler)

  The main handler function that executes the 'compare_package_versions' tool. It fetches package versions from pub.dev API, finds the specified from and to versions, compares their pubspec dependencies and dev_dependencies, and returns a structured JSON with the comparison and changes.

  async comparePackageVersions(packageName, fromVersion, toVersion) {
      const versionsUrl = `https://pub.dev/api/packages/${packageName}/versions`;
      const data = await this.fetchWithCache(versionsUrl, `versions-${packageName}`);
      const fromVersionData = data.versions.find((v) => v.version === fromVersion);
      const toVersionData = data.versions.find((v) => v.version === toVersion);
      if (!fromVersionData || !toVersionData) {
          throw new Error('One or both versions not found');
      }
      const comparison = {
          packageName,
          comparison: {
              from: {
                  version: fromVersion,
                  published: fromVersionData.published,
                  dependencies: fromVersionData.pubspec?.dependencies || {},
                  devDependencies: fromVersionData.pubspec?.dev_dependencies || {}
              },
              to: {
                  version: toVersion,
                  published: toVersionData.published,
                  dependencies: toVersionData.pubspec?.dependencies || {},
                  devDependencies: toVersionData.pubspec?.dev_dependencies || {}
              }
          },
          changes: {
              dependencyChanges: this.compareDependencies(fromVersionData.pubspec?.dependencies || {}, toVersionData.pubspec?.dependencies || {}),
              devDependencyChanges: this.compareDependencies(fromVersionData.pubspec?.dev_dependencies || {}, toVersionData.pubspec?.dev_dependencies || {})
          }
      };
      return {
          content: [
              {
                  type: "text",
                  text: JSON.stringify(comparison, null, 2)
              }
          ]
      };
  }

• src/pubdev-mcp.js:98-119 (registration)

  Tool registration in the ListTools response, defining the tool name, description, and input schema for validation.

  {
      name: "compare_package_versions",
      description: "Compare two versions of a package and show differences",
      inputSchema: {
          type: "object",
          properties: {
              packageName: {
                  type: "string",
                  description: "Name of the package to compare"
              },
              fromVersion: {
                  type: "string",
                  description: "Source version to compare from"
              },
              toVersion: {
                  type: "string",
                  description: "Target version to compare to"
              }
          },
          required: ["packageName", "fromVersion", "toVersion"]
      }
  },

• src/pubdev-mcp.js:101-117 (schema)

  Input schema defining the parameters for the compare_package_versions tool: packageName, fromVersion, toVersion.

  inputSchema: {
      type: "object",
      properties: {
          packageName: {
              type: "string",
              description: "Name of the package to compare"
          },
          fromVersion: {
              type: "string",
              description: "Source version to compare from"
          },
          toVersion: {
              type: "string",
              description: "Target version to compare to"
          }
      },
      required: ["packageName", "fromVersion", "toVersion"]

• src/pubdev-mcp.js:437-463 (helper)

  Supporting helper function that computes dependency changes (added, removed, updated) between two dependency maps, used in the handler for both dependencies and devDependencies.

  compareDependencies(oldDeps, newDeps) {
      const changes = {
          added: [],
          removed: [],
          updated: []
      };
      // Find added dependencies
      for (const [pkg, version] of Object.entries(newDeps)) {
          if (!(pkg in oldDeps)) {
              changes.added.push(`${pkg}: ${version}`);
          }
      }
      // Find removed and updated dependencies
      for (const [pkg, oldVersion] of Object.entries(oldDeps)) {
          if (!(pkg in newDeps)) {
              changes.removed.push(`${pkg}: ${oldVersion}`);
          }
          else if (newDeps[pkg] !== oldVersion) {
              changes.updated.push({
                  package: pkg,
                  from: oldVersion,
                  to: newDeps[pkg]
              });
          }
      }
      return changes;
  }

• src/pubdev-mcp.ts:444-491 (handler)

  TypeScript version of the main handler function, identical logic to JS version.

  private async comparePackageVersions(packageName: string, fromVersion: string, toVersion: string) {
    const versionsUrl = `https://pub.dev/api/packages/${packageName}/versions`;
    const data = await this.fetchWithCache<any>(versionsUrl, `versions-${packageName}`);
    
    const fromVersionData = data.versions.find((v: any) => v.version === fromVersion);
    const toVersionData = data.versions.find((v: any) => v.version === toVersion);
    
    if (!fromVersionData || !toVersionData) {
      throw new Error('One or both versions not found');
    }
  
    const comparison = {
      packageName,
      comparison: {
        from: {
          version: fromVersion,
          published: fromVersionData.published,
          dependencies: fromVersionData.pubspec?.dependencies || {},
          devDependencies: fromVersionData.pubspec?.dev_dependencies || {}
        },
        to: {
          version: toVersion,
          published: toVersionData.published,
          dependencies: toVersionData.pubspec?.dependencies || {},
          devDependencies: toVersionData.pubspec?.dev_dependencies || {}
        }
      },
      changes: {
        dependencyChanges: this.compareDependencies(
          fromVersionData.pubspec?.dependencies || {},
          toVersionData.pubspec?.dependencies || {}
        ),
        devDependencyChanges: this.compareDependencies(
          fromVersionData.pubspec?.dev_dependencies || {},
          toVersionData.pubspec?.dev_dependencies || {}
        )
      }
    };
  
    return {
      content: [
        {
          type: "text",
          text: JSON.stringify(comparison, null, 2)
        }
      ]
    };
  }