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

Annotations only supply a title and destructiveHint=true, so the description bears most of the behavioral burden. It usefully adds the channel-scoping rule and identifier format per channel, but says nothing about duplicate handling, required permissions, or failure behavior for an operation flagged destructive.

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 tightly written sentences, front-loaded with the action and scope, followed by the identifier rule and endpoint. 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 simple required-2-of-3-parameter create tool with full schema coverage and no output schema, the description supplies what an agent needs to invoke it correctly. The only gap is edge-case behavior (duplicates, permissions), which is minor at this complexity.

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 the baseline is 3, but the description adds real meaning beyond the schema's generic 'Email address or phone number, depending on the channel' by enumerating which channels map to which identifier form (email vs WhatsApp/SMS/voice).

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 (create) and resource (contact) scoped to a channel, and the API mapping 'POST /channels/{channel_id}/contacts' removes ambiguity. It is clearly distinguishable from sibling create/read tools like trengo_create_ticket and trengo_get_contact.

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 by noting the contact must belong to a channel and that the identifier depends on channel type, which is the key precondition. However, it never states when to use this versus trengo_update_contact, nor what happens if the contact already exists — no explicit alternatives or exclusions.

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