Add a post that already exists to a content item. The mutation creates no post. To add a new post, call createPost first.

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

Annotations already declare destructiveHint=true, idempotentHint=false and readOnlyHint=false, so the safety profile is covered. The description adds useful non-structured context: explicit confirmation is required, upstream field bounding is advised, and provider errors surface as failures even on HTTP 200. It still never says what the mutation actually alters on the content item.

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 title is duplicated verbatim inside the description, producing the awkward 'first..' repetition, and the trailing sentence about upstream fields and provider errors is loosely attached. Core information is front-loaded, but roughly half the text is redundant with the title or schema.

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 7-parameter mutation with no output schema and no required top-level parameters, the description covers the key behavioral facts an agent needs: confirmation requirement, the distinction from post creation, and error semantics. It leaves unclear which identifier inputs are mandatory and how the three input modes (individual fields vs payload vs payload_file) should be chosen, though the schema covers those.

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 100%, so every parameter including the nested payload and payload_file is already documented in the schema. The description's only parameter-adjacent remark ('Use upstream fields to bound data') restates the fields schema description rather than adding format or constraint detail, so the baseline of 3 applies.

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 precise verb+resource ('add a post that already exists to a content item') and immediately disambiguates from the create path by noting the mutation creates no post. An agent can distinguish this from create_post and remove_post_from_content_item 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 clear when-not condition ('creates no post') and names the alternative workflow ('To add a new post, call createPost first'), which maps to the create_post sibling. It does not explain when to prefer remove_post_from_content_item or what preconditions the content item must satisfy, so it stops short of full routing guidance.

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