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

Annotations already declare readOnlyHint/idempotent/non-destructive, so safety is covered. Beyond that the description discloses concrete per-channel behavior the schema cannot express: X counts each link as 23, email returns subject (required) and preheader (optional) while Mark doesn't send email yet, linkedin_article returns title/cover over a Markdown body and Mark doesn't publish Articles, and the CMS mapping fields reported for website channels. Only minor gap is it doesn't note caching/freshness, but the behavioral disclosure is rich.

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 purpose and the routing to get_drafting_guide are front-loaded, and the trailing Related list is compact. It is dense with channel-specific return detail (X/email/linkedin_article) that arguably duplicates the output schema, but each sentence carries usable signal and 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?

For a zero-required-param read tool with an output schema and full annotations, the description supplies everything an agent needs: what varies per channel, how to list channels, and which sibling to use for craft rules. Return values are further detailed, if somewhat redundantly with the output schema.

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 coverage is 100% and the single channel enum is fully documented with the omit-to-list behavior. The description reinforces the omit semantics but adds no syntax or format detail beyond the schema's own note, so the baseline 3 for a fully-covered single param 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 ('gives the format rules for a channel') and immediately scopes what those rules include (length limits, media ratios, meta field names/types). It explicitly distinguishes itself from get_drafting_guide on the craft-rules axis and from list_channels when no channel is given, so an agent can route without opening either 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?

Names the alternative explicitly ('For writing craft and this workspace's rules, call get_drafting_guide') and states the omit-channel branch that turns this into a listing tool. The condition selecting each behavior is spelled out rather than inferred.

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