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

Annotations already declare read-only, but the description adds genuinely new behavior: public results need no hub credential, a note flags when the org-owned side is unavailable, results are relevance-ranked and capped to genuine matches (so an empty list means no capability exists), and publicTotal reports marketplace row count. This is rich context beyond the safety hints.

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?

Purpose and scope are front-loaded, and the sentences about ranking, empty-list meaning, and routing all earn their place. It is dense and long, with minor redundancy in the closing 'Read-only. Does not write files.' that repeats the annotation.

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 no output schema, the description carries the return burden and does so: entry fields (id, label, category, short description, source), the org/public split, and publicTotal are all described. Nothing needed to call or interpret it is missing.

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 100%, so the baseline is 3, but the description adds real meaning: query is ranked against label, category, and blueprint vocabulary and capped to genuine matches, and omitting it browses the catalog with skip/limit paging. It goes beyond restating the schema fields.

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 (List) and resource (extensions available to the org plus the public marketplace) and immediately distinguishes scope from the inspection/install siblings. An agent can tell this apart from install_extension and list_extension_surfaces without opening any schema.

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?

Explicitly routes: use this to 'suggest, inspect, or install', inspect results with list_extension_surfaces / list_extension_custom_tables, and install org-wide with install_extension ONLY when the user explicitly asked. Both the alternative tools and the condition that selects them are named.

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