interceptor_chrome_devtools_get_storage_value

Retrieve specific localStorage or sessionStorage values from Chrome DevTools sessions to inspect web application data during network traffic analysis.

Instructions

Get one localStorage/sessionStorage value by item_id.

Input Schema

TableJSON Schema

Name	Required	Description
`devtools_session_id`	Yes	Session ID from interceptor_chrome_devtools_attach
`storage_type`	Yes	Storage type
`item_id`	Yes	item_id from interceptor_chrome_devtools_list_storage_keys
`origin`	No	Optional origin override (must match current page origin)
`value_max_chars`	No	Max characters for returned value (default: 20000)

Implementation Reference

src/tools/devtools.ts:1057-1160 (handler)

The handler function for 'interceptor_chrome_devtools_get_storage_value' which retrieves a localStorage/sessionStorage value by item_id using Chrome DevTools Protocol.

    "interceptor_chrome_devtools_get_storage_value",
    "Get one localStorage/sessionStorage value by item_id.",
    {
      devtools_session_id: z.string().describe("Session ID from interceptor_chrome_devtools_attach"),
      storage_type: z.enum(["local", "session"]).describe("Storage type"),
      item_id: z.string().describe("item_id from interceptor_chrome_devtools_list_storage_keys"),
      origin: z.string().optional().describe("Optional origin override (must match current page origin)"),
      value_max_chars: z.number().optional().default(HARD_VALUE_CAP_CHARS)
        .describe(`Max characters for returned value (default: ${HARD_VALUE_CAP_CHARS})`),
    },
    async ({ devtools_session_id, storage_type, item_id, origin, value_max_chars }) => {
      try {
        const session = devToolsBridge.getSession(devtools_session_id);
        if (!session) {
          return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: `DevTools session '${devtools_session_id}' not found.` }) }] };
        }

        const parts = item_id.split(".");
        if (parts.length !== 4 || parts[0] !== "st") {
          return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: `Invalid item_id '${item_id}'` }) }] };
        }
        const itemType = parts[1];
        const itemOrigin = fromBase64UrlUtf8(parts[2]);
        const itemKey = fromBase64UrlUtf8(parts[3]);
        if (itemType !== storage_type) {
          return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: `item_id storage_type '${itemType}' does not match requested '${storage_type}'` }) }] };
        }

        const { targetId } = await ensureSessionTargetIsAlive(devtools_session_id);
        const { pageUrl, wsUrl } = await getCdpPageEndpoint(targetId);

        const currentOrigin = getOriginFromUrl(pageUrl);
        if (!currentOrigin) {
          return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: `No http(s) origin available for current page URL: '${pageUrl}'` }) }] };
        }
        if (origin && origin !== currentOrigin) {
          return {
            content: [{
              type: "text",
              text: JSON.stringify({ status: "error", error: `origin '${origin}' does not match current origin '${currentOrigin}'. Navigate first.` }),
            }],
          };
        }
        if (itemOrigin !== currentOrigin) {
          return {
            content: [{
              type: "text",
              text: JSON.stringify({ status: "error", error: `item_id origin '${itemOrigin}' does not match current origin '${currentOrigin}'. Navigate first.` }),
            }],
          };
        }

        const maxChars = Math.max(0, Math.min(HARD_VALUE_CAP_CHARS, Math.trunc(value_max_chars ?? HARD_VALUE_CAP_CHARS)));
        const stType = storage_type;

        const expr = `(() => {
  try {
    const storageType = ${JSON.stringify(stType)};
    const key = ${JSON.stringify(itemKey)};
    const maxChars = ${maxChars};
    const storage = storageType === "local" ? localStorage : sessionStorage;
    const raw = storage.getItem(key);
    const v = typeof raw === "string" ? raw : "";
    const valueLength = v.length;
    const truncated = maxChars > 0 && valueLength > maxChars;
    const value = maxChars > 0 ? (truncated ? v.slice(0, maxChars) : v) : v;
    return { key, value, valueLength, truncated };
  } catch (e) {
    return { error: String(e && e.message ? e.message : e) };
  }
})()`;

        const result = await cdpEvaluateValue(wsUrl, expr) as unknown;
        if (!result || typeof result !== "object") {
          throw new Error("Unexpected storage evaluation result.");
        }
        const obj = result as Record<string, unknown>;
        if (obj.error) {
          throw new Error(`Storage evaluation error: ${typeof obj.error === "string" ? obj.error : JSON.stringify(obj.error)}`);
        }

        return {
          content: [{
            type: "text",
            text: truncateResult({
              status: "success",
              devtools_session_id,
              target_id: targetId,
              origin: currentOrigin,
              storage_type: stType,
              item_id,
              key: obj.key ?? itemKey,
              value: typeof obj.value === "string" ? obj.value : "",
              value_length: typeof obj.valueLength === "number" ? obj.valueLength : null,
              value_truncated: typeof obj.truncated === "boolean" ? obj.truncated : null,
              value_max_chars: maxChars,
            }),
          }],
        };
      } catch (e) {
        return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: errorToString(e) }) }] };
      }
    },
  );

src/tools/devtools.ts:1057-1160 (registration)

Registration of the 'interceptor_chrome_devtools_get_storage_value' tool within the registerDevToolsTools function.

    "interceptor_chrome_devtools_get_storage_value",
    "Get one localStorage/sessionStorage value by item_id.",
    {
      devtools_session_id: z.string().describe("Session ID from interceptor_chrome_devtools_attach"),
      storage_type: z.enum(["local", "session"]).describe("Storage type"),
      item_id: z.string().describe("item_id from interceptor_chrome_devtools_list_storage_keys"),
      origin: z.string().optional().describe("Optional origin override (must match current page origin)"),
      value_max_chars: z.number().optional().default(HARD_VALUE_CAP_CHARS)
        .describe(`Max characters for returned value (default: ${HARD_VALUE_CAP_CHARS})`),
    },
    async ({ devtools_session_id, storage_type, item_id, origin, value_max_chars }) => {
      try {
        const session = devToolsBridge.getSession(devtools_session_id);
        if (!session) {
          return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: `DevTools session '${devtools_session_id}' not found.` }) }] };
        }

        const parts = item_id.split(".");
        if (parts.length !== 4 || parts[0] !== "st") {
          return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: `Invalid item_id '${item_id}'` }) }] };
        }
        const itemType = parts[1];
        const itemOrigin = fromBase64UrlUtf8(parts[2]);
        const itemKey = fromBase64UrlUtf8(parts[3]);
        if (itemType !== storage_type) {
          return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: `item_id storage_type '${itemType}' does not match requested '${storage_type}'` }) }] };
        }

        const { targetId } = await ensureSessionTargetIsAlive(devtools_session_id);
        const { pageUrl, wsUrl } = await getCdpPageEndpoint(targetId);

        const currentOrigin = getOriginFromUrl(pageUrl);
        if (!currentOrigin) {
          return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: `No http(s) origin available for current page URL: '${pageUrl}'` }) }] };
        }
        if (origin && origin !== currentOrigin) {
          return {
            content: [{
              type: "text",
              text: JSON.stringify({ status: "error", error: `origin '${origin}' does not match current origin '${currentOrigin}'. Navigate first.` }),
            }],
          };
        }
        if (itemOrigin !== currentOrigin) {
          return {
            content: [{
              type: "text",
              text: JSON.stringify({ status: "error", error: `item_id origin '${itemOrigin}' does not match current origin '${currentOrigin}'. Navigate first.` }),
            }],
          };
        }

        const maxChars = Math.max(0, Math.min(HARD_VALUE_CAP_CHARS, Math.trunc(value_max_chars ?? HARD_VALUE_CAP_CHARS)));
        const stType = storage_type;

        const expr = `(() => {
  try {
    const storageType = ${JSON.stringify(stType)};
    const key = ${JSON.stringify(itemKey)};
    const maxChars = ${maxChars};
    const storage = storageType === "local" ? localStorage : sessionStorage;
    const raw = storage.getItem(key);
    const v = typeof raw === "string" ? raw : "";
    const valueLength = v.length;
    const truncated = maxChars > 0 && valueLength > maxChars;
    const value = maxChars > 0 ? (truncated ? v.slice(0, maxChars) : v) : v;
    return { key, value, valueLength, truncated };
  } catch (e) {
    return { error: String(e && e.message ? e.message : e) };
  }
})()`;

        const result = await cdpEvaluateValue(wsUrl, expr) as unknown;
        if (!result || typeof result !== "object") {
          throw new Error("Unexpected storage evaluation result.");
        }
        const obj = result as Record<string, unknown>;
        if (obj.error) {
          throw new Error(`Storage evaluation error: ${typeof obj.error === "string" ? obj.error : JSON.stringify(obj.error)}`);
        }

        return {
          content: [{
            type: "text",
            text: truncateResult({
              status: "success",
              devtools_session_id,
              target_id: targetId,
              origin: currentOrigin,
              storage_type: stType,
              item_id,
              key: obj.key ?? itemKey,
              value: typeof obj.value === "string" ? obj.value : "",
              value_length: typeof obj.valueLength === "number" ? obj.valueLength : null,
              value_truncated: typeof obj.truncated === "boolean" ? obj.truncated : null,
              value_max_chars: maxChars,
            }),
          }],
        };
      } catch (e) {
        return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: errorToString(e) }) }] };
      }
    },
  );

proxy-mcp