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ably

by io.usefulapi

Get channel message history

ably_get_channel_history
Read-only

Retrieve historical messages published to a channel, newest-first by default. REST: GET /channels/{channel}/messages.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
endNoLatest message time, ms since epoch (inclusive).
limitNoMax messages (<=1000). Default 100.
startNoEarliest message time, ms since epoch (inclusive).
channelYesChannel name, e.g. 'chat:room1'.
directionNoforwards (oldest-first) or backwards (newest-first, default).

TDQS

A3.9/5.0
Behavior3/5

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

Annotations already mark readOnlyHint, so the description only needs to add behavioral nuance. It adds 'newest-first by default' and the REST endpoint, which is useful but does not cover pagination or rate-limit behavior.

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?

Two short sentences with the core behavior first and no filler. The REST endpoint line is helpful context but slightly redundant for an MCP agent, preventing a 5.

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

Completeness4/5

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

For a read-only history tool with fully documented scalar parameters and no output schema, the description is mostly sufficient. A note on the response format or pagination would make it fully complete, but these are not critical blockers.

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

Parameters3/5

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

Schema description coverage is 100%, so the input schema already documents every parameter. The description contributes only 'newest-first by default,' which duplicates the direction parameter's schema text, so it adds no new parameter meaning.

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 uses a specific verb ('Retrieve') with a clear resource ('historical messages published to a channel') and states default ordering. This distinguishes it from sibling tools like presence history and channel details without opening the schema.

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?

The first sentence establishes a clear use case: retrieving past channel messages. It does not name alternatives or explicitly state when not to use it, so it stops short of a 5.

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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TDQS

A4/5.0
Disambiguation5/5

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.

Naming Consistency5/5

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.

Tool Count5/5

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.

Completeness3/5

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.

Resources