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

The annotations already establish that this is a non-read-only, non-destructive mutation. The description adds useful non-obvious behavior: parameters and headers are replaced wholesale rather than merged, and omitting them preserves existing rows. It does not disclose effects on other fields, validation behavior, or whether other omitted fields are preserved.

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 with the core patch semantics front-loaded and the replacement caveat immediately after. There is no filler.

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 seven-parameter mutation tool with no output schema, the description is thin: it omits the required toolId, says nothing about the other updatable fields, and does not explain what the tool returns or whether the update is validated. It covers only the replacement behavior of two fields.

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% across seven parameters, and the description only explains semantics for two of them (parameters and headers). The required toolId, url, name, httpMethod, and description fields are left entirely to the schema, so the description does not compensate for the coverage gap.

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 states a specific verb and resource ('Patch a custom tool'), which clearly distinguishes it from sibling read/list/create/delete tools. It does not explicitly name those siblings, but the mutation scope is unambiguous.

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?

It gives partial-update guidance for parameters/headers ('omit to leave them'), which implies how to use the tool for incremental changes. However, it does not say when to choose this over tools_create_custom or tools_delete, nor does it mention prerequisites such as a valid toolId.

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