post_contacts

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

Description correctly indicates a write operation (create), consistent with annotations (readOnlyHint=false). Adds context about permission requirement and behavior for new contacts, but does not disclose what happens if the contact already exists (e.g., error or update), or other behavioral traits like rate limits.

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?

Short and front-loaded with purpose and permission. The HTML break and endpoint are slightly redundant but not verbose. Efficient for a simple creation tool.

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?

No output schema. The description does not specify what the response contains (e.g., the created contact object) or behavior on duplicate contacts. Given the 6 required parameters, more detail on expected outcomes would improve completeness.

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% (all 6 parameters have descriptions). The description adds no additional meaning beyond the schema, only repeating 'Create contact'. Baseline 3 is 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?

Clearly states the action ('Create contact') and resource ('contact') and includes permission requirement. Distinguishes from sibling tools like 'delete_contacts_by_subject_id' and 'put_contacts_by_subject_id'. However, the phrase 'adds the contact to the authenticated account' is slightly vague.

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?

Implies usage for creating new contacts via 'Creates the contact if it is new', but lacks explicit when-to-use or when-not-to-use guidance. No mention of alternatives such as 'put_contacts_by_subject_id' for updating.

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