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

Annotations already cover read-only/idempotent/non-destructive, but the description adds substantial beyond-annotation context: untracked names are reported rather than fatal, no charge occurs if nothing is tracked or all lookups fail, and payment mechanics are specified ($0.05 USDC via x402 placed in _meta["x402/payment"]). No contradiction with the declared hints.

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?

Front-loaded with the verb, resource, and scope, then the routing rule, edge cases, and pricing. It is dense with helpful facts and nearly every clause earns its place, though the x402 payment parenthetical is the one clause an agent could infer from the billing context.

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?

Despite having no output schema, the description explains what comes back (per-vendor status plus a list of non-operational vendors), the failure/edge behavior, the cost model, and the alternative tool. Single-parameter, low-complexity input means nothing an agent needs to invoke it correctly is missing.

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 schema already documents the single vendors array including the 1-25 bounds and accepted name/slug/domain forms. The description restates the 25 cap and adds that untracked names are tolerated, but supplies no additional syntax or format guidance beyond the schema; 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?

States a specific verb and resource ('Check the status of ... SaaS or cloud vendors in one call') with a concrete cap of 25, and names the sibling it is not: 'Use vendor_status when you need incident detail for a single vendor.' An agent can distinguish it from vendor_status without opening either schema.

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?

Gives an explicit triggering scenario ('is my stack down?' questions) and an explicit alternative plus the condition that selects it (vendor_status for single-vendor incident detail). Nothing is left to inference about when to pick this tool.

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