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

Annotations already mark this as a write (readOnlyHint=false) and idempotent (idempotentHint=true). The description adds that the thread is created open, anchored to an immutable version, and requires comment access; also mentions rate limiting. No contradiction with annotations, though it doesn't elaborate on idempotent handling.

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 sentences with no filler; front-loads the action and object, then covers prerequisites, rate limit, and alternative tool. Every clause adds useful information.

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?

Description covers purpose, prerequisites, rate limiting, and alternative tooling; schema and output schema handle parameter details and return values. For a create-thread tool with an output schema and rich annotations, this is sufficiently complete.

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 provides full descriptions for all 5 parameters (100% coverage), including the anchor oneOf variants and idempotencyKey semantics. The description's mention of anchoring to 'whole artifact, exact text, or an HTML element' maps to the anchor parameter but adds no new syntax beyond the schema.

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 specific action 'Create a new open review thread with its first comment' and identifies three anchoring modes. Distinguishes from sibling 'reply_to_thread' by explicitly targeting new threads. Clear verb and resource.

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 instructs to use 'reply_to_thread' for existing discussions, providing a direct alternative. Also notes caller must have comment access and that comment creation is rate-limited, setting usage expectations.

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