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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description's addition is the raw endpoint mapping (GET /v1/pagamentos/{codigo}), which is mild context but says nothing about failure behavior for a nonexistent code or the shape/size of the response.

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 sentences, zero filler, with the core action front-loaded ahead of the endpoint detail. Nothing needs trimming.

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 no output schema, the description is the only place an agent could learn what a payable record contains, and it says nothing about the returned fields or not-found handling. For a simple read-by-id tool that is a tolerable gap, but it is still the weakest part of an otherwise adequate definition.

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% and the single 'codigo' parameter is fully documented in the schema, including its constraint (integer > 0) and its origin. The description adds no format, sourcing, or example detail beyond that, so the 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?

The description names a specific verb and resource ('Get one payable by code'), which cleanly separates it from the list-style siblings such as egestor_list_payables. It stops short of explicitly naming that sibling, but the singular/plural contrast makes the distinction inferable.

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?

Usage is only implied: 'by code' signals a single-record lookup, but the description never states when to use this instead of egestor_list_payables or what to do if the code is unknown. The 'from the matching list tool' hint lives in the schema, not the description, so no exclusions or preconditions are offered here.

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