Retrieve every app from a publisher that has appeared on App Store or Google Play charts, with the date each was first seen.
Every app of one publisher that we have seen on a chart, with the day each was first seen. Apps the publisher never charted are not here — we list what we measured, not what exists.
| Name | Required | Description | Default |
|---|---|---|---|
| publisherId | Yes | publisher id, e.g. from market_new_apps |
Changes observed during successful MCP inspections.
v1.5.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is low, and the description clears it by disclosing a real behavioral trait: results are measured-coverage only, not the publisher's full catalogue. This caveat is genuinely beyond what the annotations say, though it doesn't cover return format or ordering.
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?
Two tight sentences with the substantive payload (apps plus first-seen day) front-loaded, and the second sentence as a deliberate caveat. Slightly aphoristic phrasing ('what we measured, not what exists') is characterful but still earns its place as the scope boundary.
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?
No output schema exists, so the description has to sketch the return shape, and it does (apps with first-seen dates). Annotations handle the safety profile, and the coverage caveat handles expectations; only ordering/pagination and explicit sibling routing are left unstated.
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% for the single publisherId parameter, so the schema carries the parameter meaning and the 3 baseline applies. The description reinforces single-publisher scope but adds no format or sourcing detail beyond 'one publisher'.
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 states a specific resource (every app of one publisher) and a specific returned attribute (the day each was first seen on a chart), so an agent can tell what it gets. It stops short of naming the sibling it is distinct from (market_new_apps, market_charts), so differentiation from the market_* family relies on inference.
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 implied by the scope caveat ('apps the publisher never charted are not here'), which tells the agent what it cannot expect, but no explicit when-to-use or alternative tool (e.g. market_new_apps or market_charts) is named. The one-line 'e.g. from market_new_apps' hint lives in the schema, not the description.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.