Read messages

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds the ordering guarantee (oldest first) and the replyCount pivot, but says nothing about pagination continuation or what a result looks like beyond the schema's cursor hint.

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 tight sentences, front-loaded with the core verb and scope, with the sibling routing appended. No filler or restated title.

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 paginated read with a fully documented schema and read-only annotations, the description covers purpose, ordering and the one non-obvious alternative. No output schema exists, but the return shape is inferable from the cursor/pagination parameters.

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, cursor, latest, oldest and target each carry their own documentation, including accepted time formats. The description only echoes "channel or DM" and ordering, so it adds little beyond the schema; 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 recent messages from a channel or DM") and adds the ordering semantic ("oldest first"). It names read_thread as the sibling for replies, but does not distinguish itself from search_messages or list_unread, which also surface message content.

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 a concrete routing rule: use read_thread for messages with a replyCount. That is real when-to-use guidance, but it only covers one alternative and leaves the search_messages / list_unread overlap to inference.

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