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

Annotations already declare readOnly=false, openWorld=true, destructive=false, so the safety profile is partly covered. The description adds meaningful context beyond that: the message appears under the user's name, is visible to the team, reaches other people, and requires a Cotlet API key with app access. Failure/return behavior is not covered, but the extra context is substantive.

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 first two sentences largely restate the same posting/reply behavior, and 'Your team sees it on the job' overlaps with 'for your team', so there is noticeable redundancy. The confirmation and auth requirements are useful but the front-loaded content repeats itself.

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 no output schema, the description carries return-value burden but this is a simple mutation where the outcome (message posted) is self-evident. It covers scope, auth, and confirmation behavior; the main omission is nothing beyond minor failure/error context.

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%, so body, job_id, and reply_to_id are already documented in the schema. The description restates the reply_to_id semantics (threaded reply) without adding format or constraint detail beyond the schema, so the baseline of 3 is appropriate.

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 a specific verb and resource ('Post a message on a job') and clearly distinguishes the two modes: a new message under your name versus a threaded reply when reply_to_id is set. An agent can tell it apart from the read-side sibling list_job_messages immediately.

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?

Explains the condition that selects thread-reply mode (reply_to_id set) versus a standalone post, and gives explicit situational guidance about confirmation ('confirm with the user before each call' because it reaches other people). It doesn't name a read alternative, but the when/when-not is clear.

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