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

The "WRITE:" marker plus the raw endpoint (POST /{account}/contacts) reinforces the mutation semantics already implied by destructiveHint=true, so it is consistent rather than contradictory. However, it says nothing about duplicate-phone handling, whether the call is idempotent, permission requirements, or what object comes back — meaningful gaps for a create operation even allowing for the lower bar set by annotations.

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 short, front-loaded sentences with no filler; the operation type leads and the endpoint follows. Nothing is padded, though the terseness comes at the cost of substance rather than being a model of density.

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?

With 6 parameters, 3 of them required, and no output schema, the description should ideally say what a successful create returns (e.g., the new contact ID) and how failures like duplicates surface. It leaves both unaddressed, though the fully-described schema and the destructiveHint partially compensate.

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 all six parameters (including the account-slug cross-reference to textus_list_accounts and the phone_type default) are already documented in the schema. The description adds no field-level meaning beyond that, so the baseline 3 applies.

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 opening "WRITE: creates a new contact in an account" gives a specific verb (creates) and resource (contact) scoped to an account, which cleanly separates it from the read siblings like textus_get_contact and textus_list_contacts. It stops short of explicitly naming an alternative, but the create-vs-read distinction is unmistakable.

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?

There is no when-to-use guidance, no preconditions stated (the account slug requirement only appears in the schema), and no mention of what to do when a contact already exists at that number. The agent is left to infer everything about selection context from the verb alone.

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