Funnel

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

Annotations already declare a safe read-only, idempotent, closed-world operation, so the bar is lower. The description adds real value beyond them: the hard 400-day range limit, the to<=today ceiling, the project time-zone convention for dates, and a data-quality caveat that event/page/property text is reported verbatim as visitors sent it.

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?

Front-loaded with what the report produces, then constraints, then the data caveat. Efficient overall, though the final paragraph about text fidelity is tangential to invoking the tool and could be trimmed.

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?

There is no output schema, so the description must convey returns, and it does: per-step counts plus median transition times and whole-funnel time. Combined with the date-range and time-zone rules, an agent has what it needs; the remaining gaps are the funnel_subjects/funnel_segments routing decision.

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%, including step object oneOf variants, mode semantics and the 2-8 step limit, so the baseline is 3. The description's only added detail is the verbatim-text caveat; its list of 'property values, sources, campaigns and routes' actually names dimensions this tool has no parameters for, which adds no usable per-parameter meaning.

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 specific verb and resource: counts of visits/people reaching each funnel step, ordered, with median time-to-next and through the whole funnel. An agent can tell this is an ordered multi-step funnel report. It does not, however, name or distinguish itself from the sibling tools funnel_subjects and funnel_segments, which likely report on the same funnel.

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 is only implied: 'The project id and the project's today come from list_projects' plus the range constraints (at most 400 days, to at most today). There is no explicit statement of when to pick this over funnel_subjects or funnel_segments, so the agent must infer from the sibling names.

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