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

Goes well beyond the annotations: it discloses the write path (chat row created, reply persisted), the exact success payload {chat_id, reply}, the failure mode (JSON-RPC error carrying {chat_id, ai_error} rather than apology text), and the authentication requirement. That is materially more than destructiveHint=false tells the agent.

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 dense sentences, front-loaded with the action and followed by the return and error contracts; nothing is filler. The dash-heavy construction packs a lot into one sentence but remains parseable.

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 supplies the return shape and the error shape, which is the important missing piece. The remaining shortfall is caller-side: owner/repo semantics are unaddressed, which matters for a tool that scopes to one repository.

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 only 50%, and the two undocumented parameters are exactly the ones needing guidance: owner and repo are never explained (format, whether they are separate org/name fields). The description only restates 'repo' and 'message' at a high level, so it does not compensate for the coverage gap.

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 (start a new chat with a repo) and enumerates the concrete side effects: creating a chat row, sending the first user message, streaming and persisting the assistant reply. The word 'new' implicitly separates it from merjax_chat_continue, so an agent can pick between them without opening a 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?

The framing 'Start a new chat' clearly signals the opening turn of a conversation rather than a follow-up, which is the main usage decision here. It does not explicitly name merjax_chat_continue or say when to switch to it, so the alternative routing is left to inference rather than spelled out.

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