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

Annotation Contradiction: annotations declare readOnlyHint=true, but the description says the tool saves the draft to the user's files, enforces a 20-per-day draft limit, and blocks copying until an unlock. These are stateful side effects, so the read-only annotation is directly contradicted.

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?

Front-loaded with the core action and the key safety guarantee. Every sentence adds operational value, and the density is warranted by the tool's complexity, though light structure would make the many constraints easier to scan.

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?

Covers templates, body format, audience, daily limit, credit gating, and retry prohibition. The main gap is that, with no output schema, it never describes what the tool returns or how to locate the saved draft afterward.

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?

Adds meaningful detail beyond the schema: template_id is tied to expected props ('post' takes signoff; 'digest' takes intro, signoff), title/subtitle roles are clarified, and markdown versus blocks is stated as mutually exclusive. The audience line mostly repeats the schema enum, so it is strong but not maximal.

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: draft one Substack post and save it to the user's files. It also clarifies the non-publishing, non-sending scope, which distinguishes it from email draft tools and publishing-related siblings.

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 usage context: template-specific props, markdown-or-blocks exclusivity, audience values, and an explicit 'do not call this again to retry' instruction. It does not name sibling alternatives or provide when-not-to-use rules, so it stops short of a 5.

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