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

Annotations already mark readOnlyHint=true, and the description reinforces this with 'Pure analysis. Writes nothing.' It adds behavioral context about what the validation covers (e.g., PII/prohibited-content warnings), going beyond the annotation. However, it does not describe the exact return format or behavior on violations.

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 two sentences, front-loaded with the core purpose and follow-through with 'Pure analysis. Writes nothing.' Every clause adds value; no fluff or repetition of schema field names.

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 validation tool with 6 parameters and no output schema, the description covers the main inputs and behavior. It lacks explicit mention of what the function returns (e.g., a list of violations vs. a pass/fail flag), but the mention of 'warnings' and the overall scope is sufficient for an agent to invoke 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%, so the baseline is 3. The description adds meaning by tying parameters to validation rules (caption length, media requirements, hashtag ceilings, YouTube titles), which helps select and populate the correct parameters. It does not detail platformMeta, but the schema already describes it.

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 uses a specific verb ('Check a caption') and a clear resource ('against each target platform's posting rules'), enumerating concrete checks (caption length, media requirements, hashtag ceilings, clickable links, YouTube titles, PII/prohibited-content warnings). This clearly distinguishes it from sibling scheduling, drafting, and deletion 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?

'before scheduling' gives a clear when-to-use context, and 'Pure analysis. Writes nothing' implies it should be used for validation before mutation tools like sprkly_schedule_post. It does not explicitly name alternatives when not to use it, but the context is strong enough.

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