read_messages

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

With no annotations, the description carries the full burden, and it does add value beyond structured fields: chronological ordering, a hard cap of 500 that the schema does not mention, and the paging mechanism via 'before'. It still omits the safety profile (read-only nature), permissions/scope requirements, and what a returned message looks like, which matter for a tool with zero annotation coverage.

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?

The behavior sentence is front-loaded, followed by a compact aligned parameter glossary. Every line carries information; the minor cost is the slightly list-like layout, but nothing is wasted.

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 four-parameter tool with no output schema and no annotations, the invocation side is well covered (params, ordering, paging, cap). The missing piece is the response side: without an output schema, the description should say what a message object contains or how many/how paging metadata is returned.

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 0%, so the description must compensate, and it largely does: all four parameters are explained, including where channel_id originates, limit's default and max, since_hours' time-window semantics with a concrete example, and before's use for backward paging. Only limit's default is redundant with the schema.

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 messages from one channel, thread, or DM') plus an ordering guarantee ('oldest first'), which tells an agent exactly what it gets back. It does not explicitly contrast with the sibling read_server_recent, so the agent must infer that this one is scoped to a single channel/thread rather than a whole server.

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?

Useful routing hints are present for parameters: channel_id must come 'from list_channels' and 'before' is for paging further back. However, there is no explicit statement of when to prefer this over read_server_recent, and no exclusions or prerequisites, so the when-to-use guidance is implied rather than stated.

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