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

Annotations only declare readOnlyHint=true, so the description carries full responsibility for behavioral disclosure. It reveals crucial non-obvious traits: pagination is always disabled ('next_cursor is always null'), participant_count may be null for hostnames outside the top-N facet (not zero), and provider resolution uses a specific precedence mapping identical to /v1/aps. This is rich context beyond what annotations provide.

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 description is appropriately sized given the tool's complexity. It front-loads the core purpose in the first two words and then each sentence adds unique value: inclusion criteria, count semantics, provider resolution, and pagination behavior. No sentence is wasted, and the structure flows logically from definition to edge cases.

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 thoroughly explains what the tool returns (hostname, seats, provider, participant_count) and how those fields are derived. It also covers edge cases like null counts and non-pagination. Given the two optional parameters and read-only nature, the description is complete and leaves no significant questions about behavior.

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 both parameters (q and limit) are already fully described in the input schema (case-insensitive substring filter, cap on rows, defaults). The description adds no additional parameter semantics; it focuses on result interpretation and ordering rather than parameter behavior. Thus the baseline score of 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?

The description opens with a clear verb and resource: 'List SMPs'. It then specifies exactly what is listed: 'every current SMP hostname with the seat(s) and provider that sign its metadata, busiest first.' This distinguishes it from sibling list tools like list_hosts and list_providers by focusing on the SMP-specific directory.

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?

The description provides clear context for when to use this tool: when you need the SMP directory or need to see which hostnames currently home participants or carry signing certificates. It does not explicitly name alternatives or exclusions, but the scope is well-defined, which effectively tells the agent when this tool is appropriate.

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