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

With no annotations supplied, the description carries the full burden and does well: it declares read-only behavior, zero external side effects, and no mutation of database or carrier state. What it does not disclose is whether the call fans out to live carrier APIs (and therefore has latency or per-call cost) or whether returned credentials are masked or truncated, which matters for a discovery tool that exposes API keys.

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 structure is front-loaded and purposeful: capability, then the read-only safety statement, then usage, then exclusions. The only mild redundancy is the capitalized 'READ-ONLY DISCOVERY TOOL' label immediately followed by a sentence that says the same thing ('zero external side effects', 'does not mutate').

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 zero-parameter, no-output-schema, no-annotation tool, the description supplies most of what an agent needs: scope, safety profile, and routing to alternatives. It stops short of describing the shape of the returned status data (per-courier readiness flags, credential presence vs. validity), which is the one gap left by the absence of an output schema.

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?

The tool takes no parameters, so there is no parameter semantics to explain; the baseline for a zero-parameter schema applies. The description correctly does not invent or discuss inputs.

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 ("Inspect") and specific resources (operational health, configuration status, active API credentials) across named courier networks and Google Maps Platform. It is immediately distinguishable from siblings because it explicitly positions itself against track_parcel and calculate_delivery_zone_and_fee.

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 a concrete when-to-use scenario (session initialization to verify which couriers are ready for dispatch or balance checking) and explicit when-not-to-use cases with the named alternative for each: 'track_parcel' for shipment status and 'calculate_delivery_zone_and_fee' for fees. Nothing about tool selection 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.