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

With no annotations provided, the description carries the full burden, and it discloses substantial behavior: scheduled_at must be UTC (Y-m-d H:i:s), media uploads are automatic from HTTP(S) or base64 data URLs with explicit size caps (500MB HTTP, 75MB/56MB base64), awaiting_approval creates a post pending team approval, and post_type defaults to scheduled. This is rich behavioral context, though it omits auth requirements, reversibility, and response format.

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 description is a single dense paragraph with the core purpose front-loaded and every sentence carrying operational value. It is not padded, but a bit of structure (bullets or clause separation for the distinct concerns: scheduling, media, options, post_type) would improve scannability for an agent.

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 6-parameter creation tool with no annotations and no output schema, the description covers the critical decision points: scheduling format, media constraints, post-type semantics, and options sourcing. It omits the response/return shape and failure behavior, which is a gap, but the operational essentials an agent needs to invoke it correctly are present.

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 only 17% (solely the options parameter), so the description must compensate, and it does: it specifies scheduled_at's exact format, media_urls' accepted types and size limits, post_type's three valid values with default, and that options must come from get_post_options as a JSON-encoded object. This adds real meaning beyond the bare schema.

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?

The description opens with a specific verb and resource: 'Create or schedule a social media post to a single account.' This clearly distinguishes it from siblings like update_post (modification), publish_post_now (immediate publishing), and add_post_to_queue (queue addition). The single-account scope is explicit, which separates it from bulk or multi-account tools.

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?

The description implies when to use the tool through its post_type options (scheduled, draft, awaiting_approval) and mentions get_post_options as a dependency, but it never explicitly states when NOT to use this tool versus alternatives like publish_post_now or update_post. The routing guidance is implied rather than stated, leaving the agent to infer boundaries.

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