Charming

set_handle

Change the signed-in user's handle (their username) — the first segment of their friendly app URLs (https://charm.ing/<handle>/<app-name>), so changing it changes the prefix of every app URL they share. Use this to give the current user a different handle. The old handle keeps working by redirecting to the new one, so links already shared stay valid. Acts on the current signed-in user only and takes no user id. Handle rules: lowercase letters, digits, and hyphens; 3-32 chars; must start with a letter; no leading, trailing, or consecutive hyphens; some words are reserved. Rate-limited to 3 changes per rolling 30 days.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`handle`	Yes	The desired new handle. Lowercase letters, digits, and hyphens; 3-32 chars; must start with a letter; no leading/trailing or consecutive hyphens. Input is lowercased and trimmed.

Output Schema

TableJSON Schema

Name	Required	Description
`ok`	Yes	Indicates success. Errors arrive as content with isError:true.
`handle`	Yes	The new live handle for the signed-in user.
`advisories`	No	Structured non-fatal advisories, including authoring issues and unread staff feedback responses. Each advisory.summary is also appended to the text content for the LLM path.
`previousHandle`	Yes	The handle the user had before this change. Retained as an alias so old friendly URLs (`/<previousHandle>/<app>`) keep resolving (a redirect to the new handle). Empty string when the user had no prior handle.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 10, 2026

addedOutput schema / properties / advisories

Added value: +{
+  "description": "Structured non-fatal advisories, including authoring issues and unread staff feedback responses. Each advisory.summary is also appended to the text content for the LLM path.",
+  "items": {
+    "additionalProperties": false,
+    "properties": {
+      "data": {
+        "additionalProperties": {},
+        "description": "Kind-specific structured payload. Shape varies per advisory kind.",
+        "propertyNames": {
+          "type": "string"
+        },
+        "type": "object"
+      },
+      "doc_url": {
+        "description": "Optional docs pointer for this advisory kind.",
+        "type": "string"
+      },
+      "kind": {
+        "description": "Stable advisory identifier (e.g. \"legacy-bridge\").",
+        "type": "string"
+      },
+      "severity": {
+        "description": "Severity; omitted advisories are treated as 'info'.",
+        "enum": [
+          "info",
+          "warn"
+        ],
+        "type": "string"
+      },
+      "summary": {
+        "description": "Agent-facing summary. Self-sufficient; no extra context required.",
+        "type": "string"
+      },
+      "userSummary": {
+        "description": "End-user-facing summary. Set when the advisory should render in-app.",
+        "type": "string"
+      }
+    },
+    "required": [
+      "kind",
+      "summary"
+    ],
+    "type": "object"
+  },
+  "type": "array"
+}

First observedJul 15, 2026

TDQS

A4.6/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond annotations, the description discloses that URLs change, the old handle redirects so existing links remain valid, the tool is scoped to the signed-in user, reserved words may apply, and there is a rolling 30-day rate limit. This gives the agent substantial behavioral context that structured annotations do not convey.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is focused and front-loads the key purpose before adding constraints, but it is somewhat dense and repeats the validation rules already present in the schema. Still, each sentence contributes a distinct fact, so the length is justified.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the simple one-parameter schema, the output schema, and annotations, the description is sufficiently complete: it covers scope, semantics, constraints, side effects, and limits. An agent can call this tool correctly without needing additional edge-case information.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already covers handle validation and trimming at 100%, so high schema coverage raises the baseline. The description still adds meaning beyond the schema by tying the parameter to the user's app URLs and mentioning reserved words and the rate limit, which affect how the handle value should be chosen.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific verb and resource: changing the signed-in user's handle, and explains what a handle is and how it affects app URLs. It clearly differentiates this from sibling set_* and rename-style tools by scoping it to the current user and handle specifically.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

"Use this to give the current user a different handle" is an explicit usage statement, and the description adds that it acts on the current signed-in user with no user id. It provides clear context and exclusions, though it does not name alternative tools or give a when-not case beyond the current-user scope.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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