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

Annotations only declare it is a non-read-only, non-destructive write. The description adds real behavioral context beyond that: the level cannot be changed after insert and editor_updateElement supports only isHidden, required, titleIsHidden. This tells the agent about immutability and the mutation surface, which the annotations do not.

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 sentences, no filler, and the core action and level semantics are front-loaded. The trailing parenthetical listing supported props is dense but earns its place by scoping the later update path.

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-param write tool with full schema coverage and annotations, the description covers the ambiguity-prone parts (level meaning, immutability) even though it does not address ordering behavior. Nothing critical for a correct call 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?

Schema coverage is 100% so the baseline is 3, but the description adds meaning the schema lacks: that level 1 = largest, and that the level argument is locked at insert time. That is genuine semantic value, though positioning params (after/parentId/position) are left entirely to the schema.

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+resource: 'Insert a heading element.' That is unambiguous and distinct from sibling insert tools like editor_insertParagraph. It stops short of explicitly naming which sibling to prefer, but the resource is precise enough for selection.

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?

Explains how to pick a header size (level 1-4, 1 = largest) and warns the level is frozen, which subtly signals 'get it right the first time.' However, it never states when to choose this over editor_insertParagraph or other insert tools, so usage is implied rather than spelled out.

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