open_chat

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

No annotations are provided, so the description carries the full burden. It discloses the return values (turn counts and preview of last reply), which is helpful, but it does not explicitly state whether opening a chat changes the active session or affects subsequent send/get_reply calls. That side effect is implied but not stated.

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?

The description is two sentences with no redundant words. The core action and URL format are front-loaded, followed by return-value details. Every sentence earns its place.

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 single-parameter tool with no output schema or annotations, the description covers invocation and expected return values well. The only meaningful gap is the lack of explicit disclosure about session-state side effects, which is relevant in the context of sibling tools like send and get_reply.

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 0%, so the description must compensate for the bare 'chat_url' property. It does by specifying the expected URL format with an explicit example (https://chatgpt.com/c/...), giving the agent enough to construct a valid parameter value.

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 uses a specific verb and resource: 'Open an existing conversation by URL' and connects it to a clear purpose ('so you can continue it'). It distinguishes itself from siblings like new_chat and close_chat by stating it targets existing conversations by URL, and even mentions what it returns.

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 clearly implies when to use this tool: when you have a URL for an existing conversation and want to continue it. It does not explicitly list exclusions or name alternatives, but the context is sufficiently clear given sibling tools like new_chat and list_chats.

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