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

Annotations already declare destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: the 4-credit cost, that it is charged only when it returns content, and the filtering logic that excludes already-recorded targets. This is meaningful beyond the structured 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 ranking criteria are front-loaded and every clause carries information (filters, ranking, cost, mode switch). It is dense and somewhat run-on across its two mode sentences, but there is little filler to cut.

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 burden of describing the return, and it does: each target comes with where to submit, and the marketplaces mode describes its own result shape. Minor gaps remain around pagination/count interaction with results, but overall it is sufficient to call the tool correctly.

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 semantics: the marketplaces flag changes the entire result set (MCP registries, plugin lists, extension stores, awesome lists rather than directories), and it clarifies that include="launch" adds nothing while "review" pulls in G2/Capterra profiles.

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 resource (next directories to list the product on) with concrete inclusion criteria (free to list, open to this product, not already recorded, ranked by AI citation frequency). It explicitly separates itself from launch boards by naming launch_targets and distinguishes its two modes (directories vs marketplaces). An agent can tell exactly what this returns without opening the 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?

Gives explicit routing: review profiles only appear when requested via include, launch boards belong to launch_targets, and marketplaces=true switches to registries/plugin lists/extension stores/GitHub awesome lists. It also states the credit cost and that it is charged only on a successful return, so the agent knows the price of calling it.

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