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

With no annotations, the description carries the full burden. It does disclose useful non-schema behavior: the return shape ('publish status and post URL') and a metered machine-to-machine cost (0.015 USDC on Base via x402). However, it omits whether the post goes live immediately/publicly, what account authorization is required, or any rate limits.

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 and organized into Trigger/Input/Output labels, so the key facts are scannable with no filler sentences. It loses a point because the Input line duplicates the schema and does so inaccurately.

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 no-annotation, no-output-schema tool the description does cover the output and cost, which is helpful. But the parameter mismatch and the absence of any account/auth or visibility detail leave meaningful gaps for a publish action.

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?

The description advertises an 'imageUrl' (optional string URL) parameter that does not exist in the input schema, which only defines 'caption'. This is actively misleading rather than additive; an agent may attempt to pass an unsupported argument. Schema coverage is otherwise 100%, so the description has nothing legitimate to add.

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 gives a specific verb+resource ('publish an image, carousel, or caption ... to an Instagram account') and names the actor (autonomous agent), which cleanly separates it from the read-oriented sibling instagram_scraper. An agent can identify the tool's job without opening the schema.

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?

It offers a 'Trigger' condition ('when an autonomous agent needs to publish...'), but this largely restates the purpose rather than contrasting against alternatives or stating exclusions. No guidance on when NOT to use it or what to use instead for related tasks.

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