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

Beyond the readOnly/openWorld annotations, it discloses what is produced (URL and iframe snippet), that the embed is the live view stripped of bars and panels, that the host page can drive the view and take PNG snapshots via postMessage under protocol perigee:v1 documented in `embedApi`, and that star_map renders the star 'alone in the iframe'. That is substantive behavioral detail an agent cannot get from the annotations.

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 dense, front-loaded sentences: the primary output (link + iframe snippet) comes first, then the postMessage capability, then the star_map exception. The long clause stacking in sentence one costs a little readability but nothing is padding.

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 nine optional-heavy parameters and no output schema, the description covers purpose, the embed's default chrome behavior, the postMessage embedding contract, and the star_map/compare interaction. The main residual gap is the format of `id` (e.g. `star:<id>`), which is only implied indirectly through the star_map and compare parameter descriptions.

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 already 89%, so the bar is a baseline of 3; the description adds real meaning on top, notably that the embed omits bars/panels by default (clarifying panel and time_bar semantics), that the view can be paused or accelerated (rate) and followed (follow), and that star_map restricts the embed to the star alone. Only `lang` and the `id` format are left to 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?

The description states a specific verb and output: it produces a link to a live Perigee 3D view plus an iframe snippet for embedding. It also distinguishes the star special case (star_map opens the star's own 3D map with the Sun instead). It does not explicitly contrast with nearby siblings like perigee_describe_view, so it stops short of a 5.

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?

It supplies concrete usage context ('for a lesson page') and spells out a branch condition: for a star, star_map opens the 3D map with the Sun rather than the normal object view, optionally with compare. There are no explicit when-not statements or named alternative tools, so it's clear context rather than full routing guidance.

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