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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety and side-effect questions are covered. The description adds useful context beyond that — the default window framing, the new_only restriction to repos created in the last 7 days, and the equivalence to Upstar's Trending page — but says nothing about result volume, pagination via next_offset, or the tie between new_only and the week period beyond what the schema already states.

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?

It is a single dense sentence that front-loads the resource and scope before the option enumeration, with no filler clauses. It is slightly run-on with the semicolon-joined new_only clause, but every clause carries information, so trimming would cost content rather than noise.

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 an output schema present, the description need not explain return values, and annotations cover the safety profile; what remains needed is purpose, scope, and default behavior, all of which are present. The one real gap for a tool sitting among eight similarly themed siblings is the absence of any routing cue distinguishing it from emerging, spotted_early, or topic_ranking.

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 every parameter including lang, sort, period, limit, offset, detail and new_only is already documented in the schema with defaults and enums. The description only restates the sort and period choices in prose ('by star velocity or by stars gained, over 24 hours, 7 days or 30 days') and adds no syntax, format, or edge-case meaning beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 names a specific resource (fastest-rising GitHub repositories across every topic Upstar tracks) and enumerates the ranking dimensions and time windows, which is more than a restatement of the name 'trending'. It falls short of a 5 because the sibling set contains closely related discovery tools (emerging, spotted_early, topic_ranking) and the description never contrasts itself with them, so an agent cannot tell from this text alone which rising-repo tool to pick.

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 phrasing suggests this is the general broad-topic trending list, versus the niche concepts implied by siblings like emerging and spotted_early, but no explicit when-to-use, when-not-to-use, or alternative-naming sentence is present. There are also no preconditions given (none needed, since all 7 parameters are optional).

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