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

Annotations already declare readOnlyHint=true and openWorldHint=false; the description reinforces this with 'opens nothing by itself', which is genuinely useful for an agent that might otherwise expect a live call. Beyond that it discloses little — no indication of the guide's shape, length, or whether it is Plex-web-specific, and the closing note about Plex's HTTP API reads as provenance trivia rather than behavior.

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?

The operational content ('returns a step-by-step guide, opens nothing, use cotlet_browser_* to act') is front-loaded reasonably, but the trailing sentence about Plex's official API and the 'checked 5 Nov 2026' date is filler that does not help an agent decide or call. The padding sits after the key clarification, diluting it.

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?

For a zero-parameter, no-output-schema tool the description is nearly complete, but it leaves the central ambiguity unresolved: an agent still cannot tell whether it will receive collection data or a how-to guide, and which Plex surface (Media Server vs. web) the guide covers. The mismatch with the title is the most consequential gap.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The description correctly implies no inputs are needed.

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 name and title promise 'List collections in Plex', but the description says the tool 'Returns how to do it in Plex step by step (screens, buttons, fields) and opens nothing by itself' — i.e. it returns a navigation guide, not a list of collections. That mismatch with the tool's own name will mislead an agent expecting collection data, and it is not differentiated from the sibling cotlet_app_guide.

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 does route the agent onward ('then do it with the cotlet_browser_* tools in the user's Plex Cloud Browser'), which is useful sequencing guidance. But it gives no condition for choosing this over cotlet_app_guide or the plex_* siblings, and never says when this tool should not be used.

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