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

Beyond the readOnlyHint and idempotentHint annotations, the description discloses key behavioral details: it 'Includes computed point counts' and explains the sparse nature of points with a concrete example (30d daily trend with one day of matches → pointCount 1). It also states 'Not metered' and the account requirement, offering valuable context about cost and access that annotations do not cover. There is no contradiction with the annotations.

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 front-loaded with the core action ('List your organization’s Trends') and then adds necessary context in a logical order. The pointCount sparsity explanation and 'Not metered' note earn their place. The parenthetical about the Prowlo account is a bit clunky ('call it to get a signup link') but still informative. Slight redundancy in explaining Trends could be trimmed, but overall it is well-structured.

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, read-only list operation with no output schema, the description is impressively complete. It defines the domain (Trends), states what is included (computed point counts), warns about a non-obvious behavior (sparse points), and mentions both metering status and account requirements. There is no major missing context; the only optional addition would be pagination or ordering, but the description stands on its own.

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 has no parameters and the schema is empty, so schema coverage is trivially 100%. The description adds no parameter-specific info, but none is needed. Per the rubric, 0 params yields a baseline of 4, which is appropriate here since there is nothing to explain beyond what the empty schema already communicates.

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 immediately states 'List your organization’s Trends', using the specific verb 'list' with a clear resource. It further defines what a Trend is (saved queries that produce a time-series), which distinguishes it from related tools like trend_get (which likely retrieves a single trend) or trend_create/update. The scope ('your organization’s') makes the action unambiguous.

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 an important prerequisite ('requires a free Prowlo account') and notes that the tool is 'Not metered', giving cost context. However, it does not explicitly contrast with sibling tools such as trend_get or trend_list vs alert_list, nor does it state when not to use this tool. The usage guidance is implied ('list' vs 'get') but not explicitly clarified.

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