# Managing MCP tool list

> Why a 68-tool MCP server eats your fresh session context and makes an agent pick the wrong tool, and how to hide the tools a session does not need from User settings in the app.

Fixter exposes everything it can do as MCP tools, 68 of them at the time of writing
(see [MCP tools](/reference/mcp/tools/)). A debugging session uses 29 of them. This
page explains why a long tool list has a cost, and how to shorten it per user from
**User settings > Tools** in the app without losing access to anything.

## Why hide tools

Most MCP clients send every tool they know about to the model with every turn: the
name, the description and the parameter schema. Three things follow from that.

### Context

In clients that load every schema up front (Cursor, Claude Desktop and most agent
frameworks), the full Fixter tool list is about 25,600 tokens of tool definitions
before you type a word. On a 200,000-token context window that is 13% of the session.
The **Debugging** preset cuts it about in half, **Setup** by a third, and a query-only
selection takes it down to about a quarter.

| What the session sees | Tools | Tokens (approx.) |
| --- | --- | --- |
| Everything (preset **All**) | 68 | 25,600 |
| Preset **Setup** | 50 | 16,600 |
| Preset **Debugging** | 29 | 13,000 |
| Only **Telemetry and querying** | 11 | 7,300 |

Measured with the cl100k tokenizer over the server's `tools/list` response;
Anthropic's tokenizer differs somewhat. **Claude Code is the exception:** it keeps MCP
tool schemas behind its tool search and fetches a schema on demand, so there the list
costs about 700 tokens whatever you hide, and the context argument does not apply. The
next two reasons do.

### Tool choice

Several Fixter tools are near neighbours by design: `suppress_signal`,
`manage_suppression_rule` and `create_ignore_rule` each silence something different.
The more of those an agent can see, the more it has to tell apart on every call, and a
wrong pick costs a turn or a clarifying question. Hiding the tools a task never needs
removes the wrong answers from the menu. This applies in every client, including Claude
Code.

### Accidents

A session debugging a failure has no reason to see `delete_dashboard`,
`remove_alert_channel` or `delete_api_test`. Hiding them is not a permission, but it
removes the chance of an agent calling one by mistake.

The effect compounds when Fixter is one of several servers in the same client: each
server adds its own list, so each server's share is worth trimming.

## Where it is

1. In the app, open the account menu at the top right (the button shows your email) and
   choose **User settings**.

   ![The app's top bar with the account button at the far right highlighted. It shows the signed-in email; clicking it opens the menu that holds User settings.](/mcp/account-menu.png)

2. In the dialog, pick **Tools** under **MCP**. The header shows how many tools are
   active, such as `68/68 tools active`.

   ![The User settings dialog on MCP > Tools: the preset row reads All, Debugging, Setup; the Telemetry & querying group shows 11/11 active with every switch on; Reset and Save buttons at the bottom](/mcp/user-settings-tools.png)

## How to use it

The panel is a personal preference: it changes which tools the Fixter server shows
**your** sessions, and nothing else. A hidden tool cannot be seen or called by your
agent, nothing is revoked, colleagues are unaffected, and if the preference cannot be
read every tool shows. Pick a preset, adjust, save, start a new session.

1. **Pick a preset** from the row at the top. It fills in the switches below as a
   starting point; nothing is saved yet.
   - **All**: every tool, including tools Fixter ships later.
   - **Debugging**: read telemetry, triage issues, silence an alert, work an
     investigation, check API tests. No authoring or deleting.
   - **Setup**: configure rules, dashboards, channels, credentials, API tests and keys,
     plus the four querying tools you need while authoring.
2. **Adjust.** Each group has a switch (on while any of its tools is on; click to turn
   the whole group off, or on when none are) and each tool has its own. The groups are
   the headings of the [MCP tools](/reference/mcp/tools/) reference; the app writes
   "&" where this site writes "and".
3. **Save.** The button enables once something differs from what is stored; **Reset**
   discards. The header counter shows the new active count.
4. **Start a new session.** The list is read when your client connects, so the current
   session keeps the old one. In Claude Code, exit and run `claude` again. Allow up to a
   minute.

**How you know it worked:** ask the agent in the new session to list its Fixter tools.
The count matches the header in the app.

Two things to know before trimming:

- **Debugging** and **Setup** are allow-lists, so a tool Fixter adds after you saved
  stays hidden until you pick a preset again or switch it on. **All** hides nothing. A
  new tool that no group names yet appears under **Other tools** at the bottom.
- The Claude Code plugin's skills call these same tools. `/fixter:onboard` needs the
  Account tools and alert setup needs the Alerting tools, so switch to **All** or
  **Setup** before running them. The app itself never goes through MCP and is
  unaffected.