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

Annotations already cover the safety profile (destructiveHint=true, idempotentHint=true, readOnlyHint=false). The description adds genuinely useful context beyond that: the required form_template_items:write scope and the fact that the template/item identity fields are immutable.

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?

Two tight sentences, front-loaded with the action and constrained to identity and auth facts. No filler, though it stops short of the one detail (partial-update behavior) that would justify a 5.

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 9-parameter mutation the annotations carry the safety story and the description adds scope plus immutability, but it never clarifies whether omitted fields are left unchanged or cleared. That partial-versus-full-update ambiguity is a meaningful gap for an agent invoking this tool, and no output schema exists to fill 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 description coverage is 100%, so the schema documents all nine parameters (including nested config/options/visible_when), which sets the baseline at 3. The description's mention of template_id and item_key is odd because neither appears in the schema (additionalProperties is false), so it adds no usable parameter syntax and provides no detail on the update semantics of the fields that do exist.

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 ('Update an existing form template item by ID'), which is clear and identifiable. It does not, however, differentiate itself from siblings like update_form_template or create_form_template_item, nor does it explain what distinguishes this item-level update.

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?

There is no explicit when-to-use guidance or reference to alternatives. 'Update an existing ... by ID' implies the precondition that the item must already exist, but nothing tells the agent when to reach for this tool versus update_form_template or the create/delete variants.

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