Read the last N (max 100) messages held in the channel's Durable Object ring buffer at the edge. Hot path is the DO, not Supabase — same data lands in messages_meta via async flush, so cold reads / pagination beyond 100 should use mIRC_list_messages.
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | How many recent messages to return (max 100, the DO ring size). | |
| channel_id | Yes | Channel id (UUID). |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only safety, and the description adds real context: the 100-message ring size cap and the fact that the same data reaches messages_meta only via async flush, which warns about staleness/consistency. It stops short of saying what happens on an unknown channel_id or an empty/evicted ring.
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 sentences, zero filler, with the scope limit front-loaded before the routing advice. Every clause carries information an agent needs.
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?
Complete on the selection decision, the cap, and the consistency model, which is what matters for a simple 2-param read. The one gap is that with no output schema the return shape (message fields, ordering, cursor availability) is never described.
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% — limit's max/min/default and channel_id's UUID format are already documented in the schema. The description only restates the 100 cap, adding no syntax or semantics beyond structured fields, so baseline 3 applies.
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?
States a specific verb and resource ('Read the last N ... messages') plus the exact backing store ('channel's Durable Object ring buffer at the edge'). It is explicitly differentiated from the sibling mIRC_list_messages, so an agent need not open either schema to tell them apart.
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?
Gives both sides of the routing decision: the DO is the hot path for recent messages, while 'cold reads / pagination beyond 100 should use mIRC_list_messages'. The exclusion condition (beyond 100) and the named alternative are both present.
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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