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

Annotations already declare readOnlyHint=true, so the safe-read profile is covered, and the description adds the concrete REST endpoint GET /v1/compras/{codigo}. It says nothing about error behavior (e.g., unknown code) or what "full data" comprises, so it adds only modest context.

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 terse sentences with the core action front-loaded and the endpoint as a compact secondary detail. Nothing extraneous.

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 single-parameter read tool with readOnlyHint annotations and full schema coverage, the description supplies enough to call it correctly. The only minor gap is not clarifying what fields "full data" returns, though no output schema exists to govern that.

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 parameter is documented as the record code sourced from the matching list tool. The description adds no format, range, or sourcing detail beyond what the schema already provides, so 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?

"Get full data of one purchase" states a specific verb and resource, and the singular "one purchase" implicitly contrasts with the list_purchases sibling. It does not explicitly name that sibling, so it falls short of the top tier.

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 schema note "from the matching list tool" implies you first call egestor_list_purchases to obtain the code, which is useful implicit routing. There is no explicit when-to-use/when-not statement or named alternative in the description itself.

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