send_message

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

The description discloses non-idempotence ('Each call sends a new message — calling twice posts twice'), which is critical and goes beyond the annotations' idempotentHint=false. It also reveals authenticated-user posting context and that replies render threaded in clients, adding genuine behavioral insight.

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?

Three dense sentences each earn their place: purpose, usage/prerequisite/non-idempotence, and reply mechanism. The key constraint is front-loaded and there is no redundant or vague language.

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?

Given the full schema, output schema, and annotations, the description supplies the missing orchestration details: where ids come from, how replies behave, and that duplicate calls produce duplicates. An agent has everything needed to invoke this tool correctly.

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 100%, so the baseline is 3. The description adds value by telling the agent where parameter values come from (conversation ids from list_conversations, reply id from read_messages), which enriches the schema's per-field descriptions.

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 first sentence states a specific verb and resource: 'Send a message to a GroupMe group or direct-message chat.' It also clarifies that it posts as the authenticated user, which disambiguates it from read/search siblings despite not naming them.

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 explicitly says to use this 'once you know where to send' and points to list_conversations for ids, giving a clear prerequisite. It also explains the reply flow via read_messages. It stops short of explicitly saying when not to use it or naming react_to_message as the alternative for reactions, so it misses a 5.

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