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

Annotations declare readOnlyHint=true, so safety is already covered and the description's main addition is the underlying endpoint (GET /transactions). It says nothing about pagination cursor behavior, result ordering, or the default result cap, which would be genuinely useful beyond the 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?

Three short clauses with the core purpose front-loaded and no filler. The trailing 'GET /transactions' is marginal value but not disruptive.

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 13-parameter listing tool with no output schema and thin annotations, the description covers the filter surface but omits anything about the shape of returned transactions or how paging composes. Adequate as a selector, incomplete as a call guide.

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% across all 13 parameters, so the schema already documents each filter's meaning and the 1-100 limit range. The description's partial restatement ('entity, invoice, status, type and date') adds no syntax or format detail beyond that, making the baseline 3 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?

States a specific verb ('List/search') and resource ('payment transactions') and enumerates the filterable dimensions, so an agent can distinguish it from mercoa_get_transaction (single lookup) without opening the schema. It stops short of naming sibling alternatives explicitly, keeping it at 4 rather than 5.

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?

The filter list ('entity, invoice, status, type and date') implies the tool is for scoped browsing rather than single-record fetch, which gives implied usage guidance. However, it never states when to prefer it over mercoa_find_invoices or mercoa_get_transaction, so the routing is left to inference.

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