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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so safety is covered. The description adds genuinely non-obvious behavioral contract: the `complete` flag semantics (false on enumeration or read limits or unknown direction) and the instruction to disclose non-exhaustiveness, plus that results are grouped by chat, newest first.

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?

Purpose and scope are front-loaded in the first clause, and the examples and fallback guidance each carry real informational weight. It is dense and slightly run-on, but almost no clause is expendable.

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?

With no output schema, the description carries the return-value burden and does so reasonably: grouped by chat, newest first, chat_id + message id pairs usable with message_get / messaging_send_message, plus the completeness flag. A little more on pagination/limit interaction with max_chats would close the remaining gap.

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%, so the schema already documents every parameter including timezone handling, provider, chat_type, and max_chats. The description reinforces the time-window and inbound-only framing but adds little parameter syntax beyond what the schema provides, so baseline 3 is appropriate.

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 (digest of RECEIVED messages) with an explicit scope (WhatsApp/Instagram/Telegram chats within a time window) and concrete query examples. It also names the sibling tools it replaces (messaging_list_chats + messaging_list_messages), letting an agent distinguish it without opening another schema.

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?

Explicitly frames when to use it (inbound digests, 'what did I get since yesterday noon', scheduled digests) and when alternatives apply — one call instead of paginating two siblings, and LinkedIn recipients route to linkedin_resolve_person + linkedin_start_conversation. Both the selection and exclusion conditions are stated.

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