Reply to Private Conversation

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

Annotations already signal a non-read-only, non-idempotent write, so the description's job is lighter. It adds the auth prerequisite and the 'existing conversation' constraint, which is useful, but it does not disclose side effects like duplicate sends or response behavior. This is adequate but not rich.

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 short sentences with no filler. The main verb and resource are front-loaded, and the parenthetical adds the essential id-source guidance immediately.

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 mutation with four parameters and no output schema, the description covers the critical preconditions: the conversation must already exist, the id comes from pm_list, and a logged-in web session is required. It does not describe return values or error cases, but the schema handles parameter-level details, making this nearly complete.

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?

The description adds the key source for conversation_id ('id from pm_list'), which is not in the schema. The schema already documents text and dry_run, and the text property's description covers html behavior. However, with schema coverage at 50%, the description only partially compensates for the less-documented parameters.

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 action ('Reply') on a specific resource ('existing private conversation') and tells the agent where to get the conversation id (pm_list). This clearly differentiates it from new-message or read-only private-message tools.

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?

The description gives clear context: use it only for existing conversations, get the id from pm_list, and ensure a logged-in web session. It does not explicitly name pm_send as the alternative for new conversations or state exclusions, so it stops short of a 5.

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