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

Annotations already declare readOnlyHint/openWorldHint=false/idempotentHint/destructiveHint, but the description adds genuinely new operational facts: no network access, no stored state, determinism, and concrete limits (64 KB input, 1 s per call, 1 MB result). Those limits are the kind of information an agent needs to avoid a failed call and are not derivable from the annotations or schema.

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?

The purpose and limits are front-loaded and labeled (Cuándo / No para / Efectos secundarios / Determinista / Límites), which is good structure. However, the Spanish body is followed by a partial English restatement that then defers to '[EN completo / full EN: inputSchema.description]' — pure duplication of the schema description with no new content, which inflates length without adding signal.

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 an output schema present, the description needn't describe return values, and it covers the remaining essentials: read-only nature, no network, determinism, and size/time limits. The only gap is the imprecise 'Cuándo' trigger, which could lead an agent to send an OpenAPI document or a receipt to this tool instead of the dedicated sibling.

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?

There is a single required parameter with 100% schema description coverage plus an inline example, so the schema largely carries this dimension. The description adds some value by spelling out which fields inside the `card` object are meaningful and by capping the payload at 64 KB, but it does not say what happens for a structurally valid card with unknown extra fields (schema sets additionalProperties=false on the wrapper).

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 (checks an A2A Agent Card JSON) and enumerates exactly what is inspected: name, description, https url, version, capabilities, default input/output modes, skills, provider and security hints. It also states the boundary 'Structural check only,' which tells an agent this is a lint-style tool, not a protocol conformance or runtime check, and it names the sibling it is not (mcp-tools-lint).

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?

It gives an explicit negative case ('No para: revisar definiciones de herramientas MCP (mcp-tools-lint)'), which is the most valuable routing signal here given how many similarly-named lint/validate siblings exist. The positive 'Cuándo' clause is weaker and muddled, sweeping in 'una lista de herramientas, un documento OpenAPI o un recibo' — inputs that actually route to openapi-summary, tool-definition-convert or recibo-verify, so the trigger condition slightly blurs the boundary it just drew.

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