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

Beyond the annotations (readOnlyHint: false, etc.), the description discloses key behaviors: 'Does not change the article by itself' (so the agent knows a separate call is needed), 'Returns the hosted URL' with a specific markdown usage, and 'Free' (cost implications). This adds meaningful behavioral context that annotations alone do not provide.

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 a single, well-organized paragraph that front-loads the core action, then details modes, return value, side-effect caveat, cost, and conditional parameter. Every sentence earns its place—no fluff, no repetition. It is concise yet comprehensive.

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 4 parameters and an output schema, the description covers the full workflow: how to host (two methods), what to do with the returned URL, that the article isn't modified directly, the cost implication, and when the optional website_id matters. It also references the related tools needed for setup (create_image_upload) and follow-up (update_article_content). Nothing an agent needs to call it correctly is missing.

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?

Although schema coverage is 100%, the description adds substantial semantics: it explains the two mutually exclusive input modes (image_url vs upload_id), points to create_image_upload for obtaining upload_id, and clarifies that article_id determines storage and website_id is conditional on account type. These enrich the schema definitions, making the parameters easier to use correctly.

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 opens with a specific verb and resource: 'Hosts an image on the website's media host for use inside an article body.' This clearly distinguishes it from siblings like set_article_cover_image (which handles cover images) and create_image_upload (which only creates an upload session). The purpose is unambiguous and immediately actionable.

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?

The description explicitly explains when to use each parameter mode: image_url for public URLs, upload_id for local files (with a reference to create_image_upload). It also states when website_id is required (multi-website accounts, see get_account) and provides the follow-up action ('save the body with update_article_content'). This gives an agent clear routing and workflow guidance without ambiguity.

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