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

Adds substantial context the annotations cannot carry: the tool is advisory only, returns screens/buttons/fields, and performs no navigation itself, which is consistent with readOnlyHint=true and destructiveHint=false. It also discloses that no public Sendible API exists. The gap is that with zero parameters it never says the returned guide is generic rather than tailored to a specific post.

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 dense sentences, front-loaded with the action and the crucial clarification that it opens nothing. The trailing API note ("checked 20 Oct 2026") is somewhat awkward and the sentence structure is slightly convoluted, but nothing is filler.

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 parameters, no output schema and safe read-only annotations, the description covers what the tool is and what it returns at a high level, plus the required follow-up tool family. It lacks detail on the shape of the returned steps and on how the agent should decide between this and the direct scheduling siblings.

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?

The tool takes no parameters, so the schema contributes nothing to explain; baseline 4 applies. The description correctly avoids promising any inputs such as post content or date.

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 ("Schedule post in the user's own Sendible account") and immediately corrects the natural reading of the name by saying it returns instructions rather than performing the action. It does not differentiate itself from close siblings like sendible_queue_post or sendible_send_post_for_approval, so the agent must infer that distinction elsewhere.

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?

Gives clear sequencing: call this first to get the step-by-step procedure, then execute it with the cotlet_browser_* tools in the user's Sendible Cloud Browser. It stops short of explicit when-not-to-use guidance or naming which sibling handles the same task without a browser guide.

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