Features

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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false, so safety is covered. The description adds genuinely new behavioral context: the 400-day maximum range, that 'to' cannot exceed the project's today (a failure condition), that results are daily-granularity counts, and that names/paths/sources are raw visitor-supplied text, which warns the agent about data quality.

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 sentences, front-loaded with the report's identity, then constraints, then a data-quality caveat. The final sentence is long but carries non-obvious information about input text provenance rather than filler.

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 states the return shape ('daily counts' of ranked features), the hard range limits, and the time-zone convention. Missing only things like ordering guarantees, result-size caps, or rate limits, which are minor for a read-only report tool whose annotations already cover safety.

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% so the baseline is 3, but the description goes beyond it: it anchors dates to the project time zone (not stated in the schema), restates the inclusive YYYY-MM-DD format with the 400-day constraint, and ties project_id's provenance to list_projects. The kind enum is already documented in the schema.

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 concrete resource and scope: 'the most used named events or screens (page templates) of a range, with their daily counts.' An agent can tell it produces a ranked feature report, distinct from siblings like event_properties or overview. It stops short of naming which sibling to use for adjacent questions, so no explicit differentiation.

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?

Usage context is implied rather than stated: the agent learns the project_id and the project's today must come from list_projects, and that ranges are capped at 400 days ending at today. There is no explicit when-to-use/when-not guidance versus overview, events-related siblings, or event_properties.

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