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A demo Model Context Protocol server for Mercado Pago
Server has 4 tools with basic schemas and descriptions, but significant gaps limit production readiness. All tools have descriptions (10-50 chars, below ideal 50-200 baseline) and input schemas are present but minimal. create_customer has only 1 required param with no validation guidance. search_documentation has the most complete schema (4 params with enums and constraints) but lacks output schema documentation. No tool has documented return types or error recovery guidance. Parameter descriptions are sparse, 'Email of the customer' lacks format/validation hints. No tool annotations (readOnlyHint, destructiveHint, idempotentHint) despite clear risk levels. Error handling exists in code (McpError, auth retry) but tools do not guide LLM recovery paths.
Create a new customer in Mercado Pago
Get available Mercado Pago document types
Get available Mercado Pago payments methods
Search Mercado Pago documentation
No output schemas documented for any tool. LLMs cannot plan downstream calls or extract required fields. create_customer, document_types, payments_methods return types are completely undocumented.
Tool descriptions are too short (10-50 chars vs. baseline 50-200). 'Get available Mercado Pago document types' lacks WHEN to use it, WHAT it returns, and any prerequisites. Descriptions do not guide LLM selection.
create_customer parameter 'email' lacks validation guidance. No format constraint (e.g. 'valid email address'), no length limits, no examples of what constitutes valid input. LLMs may pass malformed emails.
Inferred effective spec: <=2025-11-25.
| Scored | Grade | Overall | Spec posture | Rubric |
|---|---|---|---|---|
| 2026-09-23 | F | 42 | <=2025-11-25 | v2 |
No tool annotations (readOnlyHint, destructiveHint, idempotentHint) despite clear risk levels. create_customer is marked WRITE but tool definition lacks destructiveHint. Agents cannot infer retry safety or side effects.
Error responses in code (McpError) do not guide LLM recovery. 'MercadoPago Auth error: ...' tells agent nothing actionable. No recovery hints like 'Check CLIENT_ID/CLIENT_SECRET' or 'Retry in 30 seconds'.