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

Goes well beyond the annotations by disclosing that the listed fields are replaced wholesale and 'the previous text is lost unless Buttondown's email history is used', plus that non-draft emails are rejected and status/publish date are untouched. The destructiveHint=true annotation is confirmed and explained rather than merely echoed.

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 'WRITE:' plus a single dense sentence covering action, fields, replace semantics, refusal rule and status guarantee, closed by the endpoint. No filler sentences.

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?

No output schema and sparse annotations, yet the description supplies the mutation semantics, loss warning, refusal behavior and endpoint needed to call it safely. It doesn't say what the PATCH returns, but nothing critical for a correct invocation is missing.

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 only 29%, so the description must carry weight, and it does: it maps the editable surface to subject, body, description, slug and preview image (the 'image' parameter). It omits canonical_url and adds no format guidance beyond the schema's Markdown/HTML note, so it is not fully compensating.

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 ('edit'), a specific resource ('email that is still a DRAFT'), and enumerates exactly which fields are editable (subject, body, description, slug, preview image). An agent can distinguish this from buttondown_create_email_draft and the get/list siblings without opening any schema.

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 an explicit when-not condition ('Refuses any email that is not a draft') and clarifies what the call will never do ('never changes status or publish date'), which is exactly the boundary an agent needs before choosing this over a publish/schedule path. It does not name an alternative tool for the non-draft case, so it falls short of the 5 bar.

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