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

Annotations only declare the generic profile (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false). The description adds genuinely new behavioral context: signing_secret is shown once, private/local callback addresses are refused, API key required, 1 unit cost, and a 3-watch free-plan cap.

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-loads what the tool does, then routes to the alternative, then the Inputs/Returns/Limits blocks. Every sentence carries information, though the compressed Inputs/Returns/Limits enumeration is slightly dense rather than maximally economical.

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?

An output schema exists so return values needn't be spelled out, yet the description still flags the critical one-time secret. Covers mechanism, cost, auth, callback constraints, and the sibling alternative – 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%, so baseline is 3, but the description adds real meaning beyond the schema: entity_id must come from resolve_company, and callback_url carries a hard constraint (private or local addresses are refused) that the schema's 'Your https endpoint' does not state.

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 ('Watch a company') plus the operational mechanism (signed POSTs to your https endpoint when official records change). It explicitly names the sibling it is not (what_changed) for one-off checks, so an agent can distinguish it without reading 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 a positive trigger ('monitor a supplier or customer') and an explicit exclusion with the alternative to use instead ('Don't use it for a one-off check: call what_changed'). Nothing is left to inference.

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