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

Annotations already declare readOnly/non-destructive/idempotent, yet the description adds real value beyond them: the call is free ('charges nothing'), covers the same check pipeline as a live post, and clarifies that the moderation model only renders a verdict on a real post. That last caveat is exactly the kind of caveat an agent could not infer from the annotations.

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?

Two tight sentences, front-loaded with the dry-run framing and followed by a practical before-use instruction. No filler and no restatement of the title.

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?

Since an output schema exists, return values need no explanation, and the behavioral picture (free, non-destructive, full check coverage) is complete. However, for a 4-parameter tool with a nested location object and 25% schema coverage, the description should describe what the inputs mean, and it does not.

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 25%, so the description needs to compensate but doesn't. It hints at 'the text' and implies a price, but never explains title/body/topics constraints or the nested location object (country/state/city with geonames_id), leaving most parameter semantics to a sparse 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?

States a specific verb and resource ('Dry run: runs every check a real story gets') and enumerates the checks performed (validation, price, account standing, prefilter). It is clearly distinguishable from post_story, which it names as the real-post counterpart.

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?

Explicitly says 'Use it before post_story' and lists what the agent learns from it: the price, whether the account can post yet, and whether the text would be refused. The when-to-use condition and the alternative are both spelled out.

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