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

With no annotations, the description must disclose behavior. It reveals that media_upload options are uploaded automatically when a URL is provided, including size limits, which is valuable. However, it doesn't mention whether the operation is read-only, potential side effects beyond uploads, or auth requirements.

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 efficient: the first sentence states the core purpose and examples, and the second adds necessary detail on media upload constraints. No fluff, well-organized, and the key usage guidance is front-loaded.

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 tool with one optional parameter and no output schema, the description covers usage, parameter semantics, and a key behavioral aspect (media upload). It doesn't specify the response format, but the purpose is clear enough that an agent can infer it returns a list of options. Given the simplicity, it's adequately complete.

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 schema has 0% coverage, so the description carries the burden. It explains that account_ids can specify specific accounts or, when null, all accounts, adding meaning beyond the raw type. It could be more explicit about how the parameter influences the response, but it adequately covers the main behavior.

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 clearly states the tool's purpose: retrieving supported custom options for posting, with specific examples (first comment, location, post as reel/story). It uses a specific verb 'get' and a clear resource, and is distinct from siblings like create_post or get_post_metrics.

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 explicitly advises 'Use this before creating a post to know what options are available,' giving clear timing guidance. It doesn't mention exclusions or alternatives, but no sibling tool serves a similar pre-post purpose, so the context is sufficient.

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