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

Annotations already flag destructiveHint=true, lowering the bar. The description adds useful context that only passed fields are sent (partial update semantics) and notes the underlying PUT endpoint, but it does not explain side effects, authentication requirements, or what destructive changes to membership status/level may entail.

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 description is two sentences plus an API path, front-loading the core purpose and then adding key behavioral detail. Every sentence earns its place with no redundancy or 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?

Given a fully documented 10-parameter schema and a destructiveHint annotation, the description is nearly complete for correct invocation. It covers the partial-update behavior and endpoint, though it could briefly mention side effects of membership changes or permission needs for a perfect score.

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 already documents every parameter in detail. The description briefly summarizes updatable areas (names, email, membership, custom fields) but adds no syntax or format guidance beyond what the schema provides, making the baseline of 3 appropriate.

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 (Update) and resource (an existing contact), listing the kinds of fields that can be changed (names, email, membership level/status, custom fields). This clearly distinguishes it from siblings like create_contact and get_contact without requiring the agent to open the 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?

The description implies usage by saying 'Update an existing contact,' but it offers no explicit when-to-use or when-not-to-use guidance relative to alternatives such as create_contact or get_contact. There is no mention of prerequisites, permissions, or scenarios that select this tool over siblings.

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