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

Annotations indicate readOnlyHint=false (write), destructiveHint=false, and idempotentHint=false. The description adds that the signal is 'ephemeral provider state', which is a useful behavioral detail beyond the annotations, and implies no persistent effects. It does not contradict any annotation.

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, front-loaded with the core purpose and provider scope, followed by a concise usage caveat. No redundant words or information already in the schema.

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 write tool with good schema descriptions and annotations, the description covers what it does, when to use it, and its ephemeral nature. It does not describe return values or error handling, but with no output schema and low complexity, this is acceptable. The provider restriction and usage caution are valuable context.

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 coverage is 67% (two of three params have detailed descriptions, including strong guidance on chat_id and account_id). The action param is an enum with clear options (typing/recording) that requires no further explanation. The description itself adds no parameter detail, but the schema is sufficient, so this is above baseline.

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?

The description states a specific verb ('publish'), a precise resource ('typing or voice-recording composing signal'), and a scope ('in a known chat where supported (LinkedIn Classic and WhatsApp)'). This clearly distinguishes it from sibling tools like messaging_set_chat_state or messaging_set_presence, which handle different state/signals.

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?

It provides explicit guidance: 'use only when an agent workflow explicitly needs it' and notes it is ephemeral provider state. It does not explicitly name alternatives or state when not to use it, but the 'only when needed' instruction plus provider scope gives clear context for an agent deciding between this and similar messaging tools.

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