Upload media

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

Annotations indicate readOnlyHint=false, so the description rightly implies mutation. It goes beyond annotations by disclosing that WordPress runs its image pipeline and generates thumbnail sizes, and that the tool downloads URLs before uploading. The description also states the requirement for alt_text, which is a behavioral expectation beyond the schema. Given the annotations are minimal (just non-read-only), the description adds good behavioral context, though it could mention response or error behavior.

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 compact two-sentence block that front-loads the core purpose and sources, then adds the alt_text guideline. The only minor inefficiency is a bit of parenthetical detail that could be trimmed, but overall it's appropriately sized for a complex multi-source tool.

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?

Given the tool has 13 parameters all documented in the schema Michel, the description effectively focuses on the non-obvious aspects: source selection, local vs. remote paths, and the alt_text requirement. It compensates for the lack of an output schema by clarifying the upload process (download then upload, thumbnail generation). The description is complete for an agent to decide when and how to use it.

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 100%, so per guidelines baseline is 3. The description adds value by explaining how file_path relates to the local machine, and that base64_data requires filename. It also explains the relationship between sources (mutually exclusive) and that alt_text is required for accessibility. This exceeds baseline by adding clarifications that are not in the schema, hence 4.

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 verb 'Upload' and the resource 'media library', and enumerates three distinct sources with precise names (file_path, url, base64_data). It distinguishes this from sibling tools like update_media/edit_media by focusing on creation, and even explains the meaning of file_path in the context of the local machine, which is a common source of confusion.

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 the three input sources and when to use each: file_path for local screenshots, url for remote downloads, and base64_data for raw data. It also adds a critical guideline: 'Always set alt_text for images' with rationale, which is actionable usage guidance not present in the schema. The description implicitly covers exclusions like local-network URLs being refused, guiding the agent away from invalid input.

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