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

Annotations declare read-only/non-destructive, so safety is covered. The description adds meaningful behavioral context beyond that: the default time window, the all-time escape hatch, the owners-only gate on detail, and the Java/generic no-stats limitation. These are real call-shaping details not present in the schema.

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-loads the purpose, then defaults, then constraints, then the endpoint shape. Dense but every clause carries information; the raw endpoint template at the end is slightly clunky but useful for constructing the call.

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?

Given 9 parameters documented fully in-schema, no output schema, and read-only annotations, the description covers the remaining gaps: time-window defaults, access tier, and unsupported file types. An agent has what it needs to call correctly, though pagination interaction across pages is left entirely to schema text.

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%, so the schema already documents kind, page, source, end_date, interval, per_page, start_date, user_agent, and package_url. The description reinforces the default range and mentions the URL/kind mechanics but adds little the schema does not. Baseline 3 per rules for high coverage.

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+resource (download statistics of one package version) and enumerates the three output kinds. Clear enough to separate from sibling packagecloud_get_package (metadata) and packagecloud_get_repository_installs (repo-level installs).

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?

Provides concrete usage context: default 7-day range, start_date=19700101Z for all-time, pass package_url. States an important exclusion (Java and generic files have no download stats) and an access restriction (detail is owners-only). No sibling tool is named as an alternative, so not a 5.

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