copy_message

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

With annotations covering read/write/idempotency hints (readOnly=false, idempotent=false), the description adds the meaningful behavioral difference of omitting the 'Forwarded from' header. It also discloses that captions can be changed, going beyond what annotations provide.

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 one focused sentence with no filler. It front-loads the core action and adds a key differentiator in parentheses, earning 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?

The description defines the core purpose and one option, but with 12 parameters and no output schema, it leaves out information about return values, optional parameters, and edge cases. For an agent to use this tool confidently, more context about behavior and return format would be helpful.

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?

Only the 'caption' parameter is addressed ('Can change caption'), while 12 parameters exist and schema description coverage is only 8%. The description fails to clarify the required parameters (chat_id, from_chat_id, message_id) or other optional ones, so it does not compensate for the low schema coverage.

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 ('Copy a message') and immediately distinguishes itself from forwarding by noting 'sends without Forwarded from header'. It also clearly positions itself against the plural copy_messages tool by adding 'Can change caption'.

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 parenthetical explains a key use case ('sends without Forwarded from header'), which implies when to use this over forward_message. It also mentions caption capability, offering clear context for selection. However, it does not explicitly state when not to use it or name alternative tools.

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