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

With no annotations, the description carries the full transparency burden. It discloses that the catalog contains both built-in and custom signals, and that built-in rows carry audited spec metadata. It does not mention side effects (none expected) or rate limits, but the listing behavior is clear. It adds meaningful content beyond the tool name.

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 concise sentences: the first states the core purpose, the second summarizes the metadata content, the third gives usage guidance. Front-loaded and free of fluff.

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 read-only listing tool with three optional parameters and no output schema, the description provides a clear picture of the catalog's contents and the intended use. It gives enough detail to understand what the response contains (signal names, metadata fields), though it doesn't enumerate every field or pagination details.

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 description coverage is 100%, setting a baseline of 3. The description adds extra meaning by explaining that `builtin` refers to columns on the schema and `custom` refers to the caller's custom signals, which clarifies the enum values beyond the schema text.

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 the specific verb 'List' and the resource 'unified signal catalog', then details exactly what that catalog contains (built-in + custom). It distinguishes itself from siblings by explicitly stating the catalog's purpose: discovering available `q=` clauses and signal names before composing a scan.

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 explicit usage context: 'Use to discover what `q=` clauses and signal names are available before composing a scan.' This tells the agent when to call it, though it doesn't name alternatives or exclusions. That places it at 4 rather than 5.

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