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

The description adds substantial behavioral context beyond the readOnlyHint annotation: it explains that participant_count can be null rather than zero when outside a bounded top-N facet, that provider resolution follows a specific precedence from the most-recent open signing cert, that 'provider' and 'owner' have distinct semantics, and that pagination is disabled with next_cursor always null. This is exactly the kind of edge-case disclosure that helps an agent interpret results correctly.

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 dense but every sentence earns its place: it starts with the core definition and then methodically covers membership criteria, count semantics, provider resolution, owner/provider distinction, and pagination. Nothing is redundant, and the structure makes a complex directory semantics easy to follow.

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 and only a readOnlyHint annotation, the description carries the full burden of explaining what the tool returns and how to interpret it. It covers the key output fields (hostname, seats, provider, participant_count, owner), explains the null-count edge case, defines provider resolution precedence, and clarifies pagination behavior. This is complete enough for an agent to call the tool and correctly interpret its results.

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 input schema already documents both parameters fully with 100% coverage: q is a case-insensitive substring filter and limit caps rows with a default to all. The description does not add further parameter-specific detail, so the baseline score of 3 applies. It does add surrounding context about result ordering and non-pagination, but that is behavioral rather than parameter semantics.

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 specific verb and resource ('List SMPs') and immediately defines the SMP directory as 'every current SMP hostname with the seat(s) and provider that sign its metadata, busiest first.' It clearly differentiates this from the many sibling list_* tools by specifying exact inclusion criteria (hosts participants or carries an open smp-signing certificate).

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 implies when to use the tool by fully specifying what it returns, but it does not explicitly state when to prefer it over siblings like list_hosts or list_providers, nor does it mention any exclusions. The purpose is clear enough that an agent could infer usage, but no direct routing guidance or alternative names are provided.

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