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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes well beyond them by enumerating what the preview returns per account: rendered text with signature and short links, length vs. limit with over_by, media, format, thread parts, first comment, problems and warnings, resolved time, approval wait, and the refusal payload. This is unusually rich behavioral disclosure for a no-side-effect tool.

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 key fact — same args as create_post, saves nothing — is front-loaded, and the long enumeration of returned fields is information-dense rather than padded. The middle sentence is a run-on list that could be broken up, but no clause 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?

With 11 parameters, nested objects, and no output schema, the description compensates well by describing the return contents in detail. Remaining gaps are minor: nothing about authentication or what happens when no accounts or media are supplied, but an agent has enough to call it correctly.

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 100% and the nested options object is documented exhaustively, so the schema carries the parameter burden. The description adds only that the argument set is identical to create_post and that values are resolved per account (signature, short links, resolved time), which is useful but not substantive parameter-level clarification beyond the 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 opening sentence states a specific behavior: it takes the same arguments as create_post and saves nothing, which is a dry-run verb+resource an agent can immediately distinguish from create_post and from the read siblings like get_post. The title reinforces it without being the only signal.

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?

"Use it to fix everything in one turn and to show the user each network's version" gives an explicit when-to-use and an intended workflow. The create_post relationship ("what create_post would answer instead") implicitly defines the alternative, but there is no explicit statement of when not to use it or of prerequisites such as needing accounts/media already uploaded.

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