Create or replace a push/device token for a user.
| Name | Required | Description | Default |
|---|---|---|---|
| token | Yes | The token string | |
| device | No | Device metadata | |
| user_id | Yes | The user ID | |
| provider_key | Yes | Push provider |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description discloses the 'replace' behavior, which is not explicitly stated in the annotations (they only mark idempotentHint true). However, it does not add context about auth requirements, side effects beyond replacement, or rate limits, so it adds only marginal value beyond the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single, compact sentence with no filler. The core action and target resource are front-loaded, making it easy for an agent to quickly scan and understand the tool's purpose.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool is relatively simple and the schema covers all parameters, while annotations cover safety and idempotency. However, the description omits any mention of when to use this instead of the closely related 'patch_user_token' or bulk token operations, and it does not clarify expected outcome or error scenarios, leaving room for ambiguity.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already documents all parameters. The description adds no additional meaning about parameters, such as how 'provider_key' or 'device' interact with the replace behavior. This meets the baseline but provides no extra value.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description 'Create or replace a push/device token for a user' states a specific action and resource, clearly identifying what the tool does. It avoids tautology and is distinct from siblings like 'delete_user_token' or 'patch_user_token', though it does not explicitly name any alternative.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided on when to use this tool versus alternatives such as 'patch_user_token' or 'bulk_add_user_tokens'. The description only restates the core functionality, leaving the agent to infer selection criteria from the tool name alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Tools are mostly organized as distinct resource/action pairs, but several clusters are easy to confuse: list subscription tools (add_subscribers_to_list vs bulk_subscribe_to_list vs subscribe_user_to_list), message vs message-content vs message-history retrieval, and the many journey/journey-template list/get tools. Detailed descriptions rescue most selections, but the sheer number of near-identical verb/resource names creates real misselection risk.
Almost all tools follow a snake_case verb_noun pattern (create_, get_, list_, replace_, send_, publish_, archive_). Minor deviations keep it from a perfect score: courier_installation_guide is noun-first, and add_bulk_users sits awkwardly next to the bulk_add_* family, but the overall convention is predictable and readable.
144 tools is an extreme working-set size for an agent to hold and choose from, far beyond the reasonable 3–15 range. Even for a broad platform like Courier, this should be split into focused sub-servers (templates, journeys, users, lists, preferences, etc.) to remain usable.
The surface is remarkably comprehensive, covering sending, templates, journeys, automations, users, tenants, lists, preferences, providers, routing, brands, audiences, translations, digests, bulk jobs, and audit events. Notable gaps exist—automation template CRUD and digest schedule management are missing—but most workflows can still be completed with workarounds.
