ably_list_channelsEnumerate channels that are currently active in the app. Requires the API key to have the 'channel-metadata' capability. REST: GET /channels.
| Name | Required | Description | Default |
|---|---|---|---|
| by | No | Return channel ids only ('id', default) or full details ('value'). | |
| limit | No | Max channels per page (<=1000). Default 100. | |
| prefix | No | Only return channels whose name starts with this prefix. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already convey readOnlyHint=true, and the description adds useful behavioral context by disclosing the required API-key capability and the specific REST endpoint. It also scopes the result to currently active channels. No annotation contradiction exists and no destructive behavior is implied.
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?
Two short sentences carry the purpose, scope, permission requirement, and REST verb/path. Every element earns its place; there is no repetition of the title or filler.
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?
For a simple list operation with no output schema, the description and annotations cover authentication, scope, and the REST contract. It does not describe the return format or pagination behavior, but the schema documents limit and defaults, and the request is read-only, so the remaining gap is minor.
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?
All three parameters (by, limit, prefix) are fully described in the JSON schema, including defaults and constraints, so the description need not repeat them. The tool description adds no extra parameter semantics beyond the schema, giving the standard baseline of 3.
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 states a clear action ('Enumerate channels that are currently active') and identifies the resource ('in the app'), which differentiates it from siblings that handle account stats, channel details, presence, or history. The REST endpoint reference reinforces the operation. This is more than sufficient for an agent to select the correct tool.
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?
The description gives an explicit prerequisite (API key must have 'channel-metadata' capability) and the REST path, but it does not mention alternatives or state when not to use this tool. Context such as 'currently active' implies the use case, yet no comparison to sibling tools like ably_get_channel_details is provided.
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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Every tool targets a distinct resource and action: account-level stats, app-level stats, channel details, history, presence, presence history, service time, and each control-plane listing (apps, keys, namespaces, queues, rules) are clearly separated. The only potentially confusing pair is account stats vs app stats, but their descriptions explicitly differentiate account-wide vs API-key-scoped usage.
All tools use a uniform 'ably_' prefix followed by a consistent verb_noun pattern: get_ for single resources, list_ for collections, publish_message for the write action, and whoami for token details. There are no mixed casing styles or inconsistent verb choices.
Fifteen tools is within the ideal range and each one covers a meaningful Ably capability, from control-plane inspection to channel data retrieval and publishing. The count feels justified given the breadth of Ably's API surface, with no redundant or filler tools.
The read side is well covered: stats, channel details, history, presence, and control-plane listings all have dedicated tools, and message publishing provides one write path. However, there are no create/update/delete operations for apps, keys, namespaces, queues, or rules, so lifecycle management is largely absent and an agent could not perform common administrative workflows.