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

No annotations are provided, so the description carries the full behavioral burden. It does disclose the return content (capabilities plus supplier counts), which signals a read-only discovery operation, but it says nothing about auth requirements, result set size, or pagination for what could be a large capability index.

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?

Three short sentences, all front-loaded: what it returns, when to call it, then the two routing alternatives. Every sentence carries distinct information and none restates the title.

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 no output schema, the description usefully characterizes the return shape ('capabilities ... with supplier counts'), which is what an agent needs here. It is close to complete for a zero-parameter discovery tool, though it omits any note on result volume or ordering.

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 zero parameters, so there is nothing for the description to clarify beyond the schema; the baseline for a parameterless tool applies. The description's note about supplier counts per capability is relevant framing but is not parameter guidance.

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 ('Returns the capabilities currently indexed by the SAAX Router') plus the payload detail ('supplier counts per capability'). It also explicitly separates itself from the two nearest siblings, get_routing_fee and get_protocol_info, so an agent can disambiguate without opening schemas.

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?

'Call this to discover what can be routed' gives the triggering condition, and it names two alternatives with the exact condition that selects each ('For pricing of a specific capability, use get_routing_fee', 'For protocol overview, use get_protocol_info'). Nothing about when-to-use 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.