Open Agent Marketplace Lab

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

Annotations already establish readOnly, idempotent, non-destructive behavior, so the bar is lower. The description still adds value by disclosing the content of the read ('native API and downloadable client') and explicitly clarifying that it performs no enrollment or transaction, which sharpens the boundary against an action tool.

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?

Three short sentences, front-loaded with the core purpose and with no filler. The final exclusion sentence is compact and earns its place, though the middle sentence about API/client is a slightly loose detail.

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 one-parameter, read-only tool with no output schema, the description covers purpose, content, and the key non-mutating constraint. Only the role-to-output mapping is left unstated, which is a minor 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?

Schema coverage is 0%, so the description must compensate for the single 'role' enum. It does partially, by naming 'buyers and providers', which grounds the two enum values, but it never says that the role parameter selects which set of instructions is returned.

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 gives a specific verb+resource ('Read how ... can join') and scopes it to outside buyers and providers. It is clearly distinct from marketplace_status, but never names or contrasts with that sibling explicitly, which is what a 5 requires.

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?

'Does not enroll or transact' is a useful when-not signal, telling the agent this is informational only. However, it offers no positive trigger conditions and no named alternative for the actual enrollment path, so routing guidance is only implied.

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

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

The annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered. The description's 'does not register agents or spend money' largely restates the read-only nature, though framing it as concrete user-facing consequences adds marginal value. It says nothing about return format or data freshness.

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 zero filler, and the capability list is front-loaded before the negative constraint. Nothing could be cut without losing information.

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, read-only, closed-world tool with no output schema, the description covers the essentials by naming the data categories returned. It could be slightly richer about the shape of the returned status, but it is adequate for the tool's low complexity.

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 per the rubric the baseline is 4. The description appropriately spends no words on argument semantics.

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 gives a specific verb ('Read') and enumerates the resource contents: public marketplace availability, sandbox scope, service category, and joining links. It is clear what the tool returns, but it does not differentiate itself from the sibling marketplace_joining_instructions, which it arguably overlaps with via 'joining links'.

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?

The second sentence provides negative guidance ('does not register agents or spend money'), which implies a read-only inspection use case, but there is no explicit when-to-use statement and no routing to or away from the sibling marketplace_joining_instructions. Usage must be inferred.

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