send_message

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

No annotations provided, so description carries full burden. Describes side effect: 'creates a new visible message in the space.' Mentions required OAuth scope. Lacks discussion of rate limits or other constraints, but still provides strong behavioral context.

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?

Very concise: three short sentences with clear front-loading. Every sentence adds value (purpose, side effects, alternatives, scope). No fluff.

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 output schema present, no need to describe return values. Description covers purpose, side effects, threading, required scope, and alternatives. Complete for an agent to use the 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 description coverage is 100%. Description adds minimal parameter-specific detail beyond schema; it mentions threading and markdown but those are already in schema. Baseline 3 due to high 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?

Clearly states 'Post a text message to a Google Chat space (optionally threaded).' Uses specific verb 'post' and resource 'text message'. Distinguishes from siblings by explicitly naming alternative tools for reactions and listing messages.

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?

Explicitly provides when to use this tool vs alternatives: 'For adding an emoji reaction... use create_reaction. For listing... use get_messages.' Also mentions required OAuth scope and side effects.

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