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

Annotations indicate idempotent and non-destructive, which is consistent. Description doesn't elaborate on side effects, validation, or requirements beyond basic update. No annotation contradiction.

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?

Single sentence, 16 words, efficient and front-loaded with the action. No filler or redundant information.

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?

Covers the basic update purpose but doesn't mention the full range of configurable fields (rate limit, timeout, description, etc.) or the required id. Could be more comprehensive for a tool with 8 parameters.

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 schema already describes parameters. Description adds marginal value by naming example parameters (endpoint, auth, request template) but doesn't exceed schema's clarity.

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?

Description uses specific verb 'modify' with resource 'existing custom API tool' and lists aspects like endpoint, authentication, request template. It clearly distinguishes from siblings which update other entities (bots, contacts, etc.) or create tools.

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?

Clearly implies use when updating a custom tool's configuration. Doesn't explicitly state when not to use or mention alternatives like recreating the tool. Could provide more context on prerequisites.

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