WordPress: Upload media chunked chunk

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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the mutation/safety profile is covered. The description adds genuine behavioral context with the in-order arrival requirement, which combined with non-idempotency implies a retry could damage the session. It does not explain out-of-order or duplicate handling, chunk size limits, or session expiry, so it adds some value rather than rich behavioral context.

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?

Three short sentences, front-loaded with the action, then the constraint, then the routing preference. No filler and no repetition of the title.

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?

With five parameters, one of them an unexplained optional hash, and no output schema, the definition leaves the agent guessing about verification behavior and return values. It does cover the essential call mechanics (append, order, fallback routing), which is adequate for a low-complexity chunk operation but not thorough.

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 0%, so the description must carry all parameter meaning. It clarifies data_b64 (base64 chunk payload) and index (ordering starts at 0) but leaves session_id, site, and especially the optional chunk_sha256 entirely unexplained — an agent cannot tell whether chunk_sha256 is a validation checksum that will cause rejection on mismatch.

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?

States a specific verb and resource: 'Append a single base64-encoded chunk to a chunked upload session.' The phrase 'single ... chunk' plus the fallback framing makes it clearly distinguishable from start/finish/abort/status siblings without opening any 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?

Gives a hard sequencing rule ('Chunks must arrive in order starting at index 0') and routes the agent away from this tool when an upload_url from upload_media_chunked_start exists, calling itself the 'portable fallback.' It stops short of saying what to do after the last chunk (i.e., call the finish tool), so the usage picture is clear but not fully closed.

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