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

With no annotations, the description carries the full burden and does well: it discloses the auth model (Coach-Token owner only, staff credentials denied), the default state (private inactive draft), the publish/is_active invariant, and the slug-conflict failure mode. It does not cover validation-failure behavior, idempotency, or rate limits, so it stops short of exhaustive.

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 action and auth constraint, then progressively details payload shape and edge cases; almost every clause carries information. It is dense and run-on in places (bullets would aid scanning), but not padded.

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 tool with a complex open nested payload, no annotations, and no output schema, the description covers auth, defaults, invariants, error handling, and even summarizes the return (ID, revision, publication flags, URLs). Minor ambiguity remains around several optional payload fields and failure semantics, but nothing critical to a correct call 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 coverage is 0% and payload is an open nested object, so the description must compensate — and it does, enumerating slug, title/description/slugs/cover_alt ru/en maps, parts structure, tags, localized covers, and the AUDIO-specific fields (file_name, file_base64, optional description/order). The token parameter itself is only implied via 'active Coach-Token owner' rather than directly documented.

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+resource ('Create a material') and immediately scopes the caller ('as the active Coach-Token owner only'). It is clearly distinguishable from siblings like online_article_update, online_article_publish, and online_article_audio_set, which are named or implied by context.

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?

Explicit when/when-not routing: creation with a required stable slug here, but 'To attach validated MP3 audio to an existing own draft part use online_article_audio_set.' It also states the publish precondition ('Set publish:true only after approval') and the slug-conflict protocol ('list/get before retry; never duplicate').

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