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

Annotations supply only destructiveHint=true, so the description does add value: it flags this as a persistent WRITE on a 'real' entity and names the endpoint POST /entity. However, it omits idempotency/repeat-call behavior, permission requirements, and the fact that the entity will be visible to real counterparties — material gaps for a create-with-side-effects call.

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 packed sentences with the WRITE marker and the resource front-loaded, followed by the payload hint and endpoint. No filler or redundancy.

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 7 parameters, a nested profile object, and no output schema, the description should at least tell the agent what comes back (the new entity ID) for follow-up calls like mercoa_get_entity or mercoa_create_invoice, and mention that no fields are strictly required. It leaves those gaps.

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 all seven parameters, setting the baseline at 3. The description's mention of 'role flags, accountType, and a nested profile object' restates schema content rather than adding format rules or noting that email/foreignId are optional.

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 + resource ('creates a real entity') and enumerates the role variants (customer/vendor/payor/payee), which cleanly separates it from the read siblings (mercoa_find_entities, mercoa_get_entity) and from mercoa_create_invoice. An agent knows immediately this is the entity-creation tool.

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 explicit when-to-use guidance: it never says to search first with mercoa_find_entities to avoid duplicates, nor when to prefer this over creating an invoice with a new entity. Usage is only implied by the verb 'creates'.

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