PayGate MCP — Monetization Gateway for AI Agents

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

Annotations already provide readOnlyHint and idempotentHint, and the description adds context beyond that by detailing the output (paid calls, gross revenue, commission, net revenue per tool) and noting the api_key must come from register_server. This is useful behavioral information without contradicting 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?

The description is two sentences, front-loaded with the main purpose, and every sentence provides actionable value: what it reports, when to use it, and what it returns. No filler or redundancy.

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?

Given the tool's simplicity (1 parameter, no output schema, read-only semantics), the description is complete: it covers purpose, usage triggers, return contents, and required key provenance. No additional context is necessary for an agent to select and invoke it 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?

The schema already covers the single parameter with 100% coverage ('Your seller key'), so the baseline is 3. The description adds meaning by specifying the api_key is specifically from register_server, which is a helpful cross-reference beyond the schema's generic description.

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 uses a specific verb and resource: 'Report how much the user has earned selling their tools.' It clearly distinguishes itself from siblings by focusing on earnings and explicitly lists the returned metrics (paid calls, gross revenue, commission, net revenue).

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 description explicitly lists when to use this tool (when they ask about sales, revenue, income, how much they made, how many calls were paid, or which tool sells best), providing clear usage context. It does not explicitly mention when not to use or name alternatives, so it does not fully meet the 'explicit alternatives' bar for a 5.

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?

Annotations already declare readOnlyHint and idempotentHint, so the safe-read nature is covered. The description adds context by outlining the exact return fields (proxy URL, payout destination, commission rate, listed tools with prices) and the prerequisite api_key from register_server. This is meaningful behavioral transparency beyond the annotations, though it doesn't cover errors or rate limits.

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 description is compact, using three sentences to cover purpose, use cases, return contents, and a prerequisite. It is front-loaded with the primary action and avoids redundant phrasing. No wasted words.

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 a single parameter and no output schema, the description adequately explains the tool's behavior and returns. It covers the key use cases and the required authentication context. The description is self-sufficient for an agent to select and invoke 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?

The schema already describes api_key as 'Your seller key' (100% coverage). The description enriches this by specifying that the key comes from register_server, which is a helpful source detail. Since the baseline for full schema coverage is 3, this additional context warrants a 4.

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 clearly identifies the tool as retrieving the user's current sales listing ('Review what the user currently has for sale'). It enumerates specific use cases and distinguishes it from sibling tools like set_tool_price by positioning it as a pre-change check. The verb+resource combination is specific and unambiguous.

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 states when to use the tool: when the user asks about what they're selling, prices, money destination, or before changing a listing. It implies not to use it for making changes, which differentiates from set_tool_price. However, it doesn't name sibling alternatives explicitly or state exclusions, so a 4 is appropriate.

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?

Annotations already declare readOnlyHint and idempotentHint. The description adds useful context: browsing is free, requires no key, and returns price and endpoint for each tool. There is no contradiction, and the additional details go beyond the annotations without overexplaining.

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 description is four sentences, each earning its place. The primary purpose is front-loaded, followed by use cases and return details. No fluff, no repetition, and it is optimally sized for the tool's simplicity.

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?

Despite lacking an output schema, the description explicitly mentions what is returned (price per call and endpoint) and access requirements (free, no key). The tool is a simple list with three optional filters already documented in the schema. This is sufficient for an agent to invoke it 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?

All three parameters (search, max_price_usd, verified_only) have schema descriptions, giving 100% coverage. The description does not add extra meaning to these parameters beyond what the schema already provides, so the baseline of 3 is appropriate.

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+resource ('Find a paid tool' / 'Returns every tool on the market'), explains what it provides (price per call and endpoint), and differentiates from siblings focused on earnings, listings, and registration. This is unambiguous and immediately tells the agent what the tool does.

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 description explicitly states when to use: when the user needs a capability you lack and is willing to pay, or asks about available paid tools/APIs. It also notes that browsing is free and needs no key. However, it does not mention when not to use it or point to alternatives like get_my_listing or register_server, so it lacks explicit exclusions.

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 description discloses critical behavioral details beyond the annotations: the non-custodial payment model (buyers pay directly on-chain, no commission), the fact that the server is never modified and needs no payment code, and that the api_key is shown only once and must be saved. These are essential operational traits not captured by readOnlyHint, openWorldHint, idempotentHint, or destructiveHint.

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 description is a compact paragraph, front-loaded with the core purpose and then covering usage context, payment model, server requirements, and return values. Each sentence earns its place; the list of synonyms is slightly redundant but reinforces the trigger conditions, and there is no filler or repetition.

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?

Given there is no output schema, the description adequately explains the return values (proxy URL and once-only secret api_key), prerequisites (HTTPS and tools/list), and the critical warning to save the key. It also covers side effects (server never modified) and the payment model, making it sufficient for accurate invocation.

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 description coverage is 100%, so the baseline is 3. The description adds value by specifying that target_server_url 'must be publicly reachable over HTTPS and answer tools/list' — a requirement not present in the schema. It also contextualizes wallet_address within the direct on-chain payment model, though most parameter semantics remain in 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 begins with 'Start charging for an MCP server the user owns' — a specific verb and resource. It then enumerates synonyms (monetize, sell, charge, etc.) and clearly distinguishes this from sibling tools like get_earnings, list_registered_servers, or set_tool_price by focusing on the act of registration/monetization.

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?

Provides explicit when-to-use guidance: 'Use when they want to monetize, sell, charge for, get paid for...' It also adds a prerequisite (the user owns the server) and positions the tool as the entry point by stating 'every other seller tool needs it.' This clearly differentiates it from read-only or update siblings.

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?

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=true. The description adds the api_key requirement and clarifies the unlist action, but it introduces an inconsistency: it says 'make a tool free' while the schema states price_usd minimum is 0.01, so the claimed behavior cannot be achieved as described. This lowers transparency.

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 sentences, front-loaded with the primary action, followed by clear use cases and a requirement. Every sentence earns its place with no fluff or repetition of schema details.

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?

The tool is a simple mutation with good annotations and high schema coverage. The description covers the main use cases and prerequisite but leaves a behavioral gap around the 'make free' vs. minimum price contradiction, and does not mention what happens on unlist (e.g., whether is_active=false is required). It is adequate but not fully complete.

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 description coverage is 100%, so the baseline is 3. The description adds context about api_key origin ('from register_server') but does not add meaningful semantics for other parameters beyond the schema. In fact, it conflicts with price_usd's minimum via the 'make a tool free' phrase.

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 clearly states the tool's purpose with specific verbs and resource: 'Reprice or unlist something the user already sells.' It enumerates concrete use cases (raise/lower price, make free, pause selling, take off market) which fully distinguishes it from sibling read-only tools.

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 description explicitly states when to use the tool ('Use when they want to raise, lower or change a price...') and mentions a prerequisite (requires api_key from register_server). It does not explicitly name alternatives or exclusions, but the context is clear given the sibling list, so it misses the top level only by not saying 'instead of X'.

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 description discloses the verification mechanism (fetches the URL and confirms the token) and the consequence (earning a trusted badge), adding context beyond what annotations provide. It also notes the dependency on the api_key from register_server. These details are useful and do not contradict any annotations, though failure behavior is not described.

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 description is a few sentences long and front-loads the core purpose before explaining the mechanism and benefits. The sentence about buyers filtering verified sellers is somewhat promotional but still contributes to understanding the value. Overall, it is concise and structured effectively.

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?

The tool is simple (one parameter) and the description covers the verification process and outcome. However, there is no output schema, and the description does not mention what happens on failure or the structure of the response. Additionally, the mismatch between the schema (api_key not required) and the description (requires api_key) leaves an incomplete and slightly confusing picture.

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 schema already describes api_key as 'Your seller key.' The description adds that the key comes from register_server, providing extra context. However, the description says it is required while the schema lists it as not required, causing slight confusion. Despite this, the added context is helpful.

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 clearly states the tool's purpose: proving ownership of a listed server to earn a trusted badge. It uses a specific verb ('Prove') with a specific resource ('ownership of the server they listed'), and it distinguishes from sibling tools by focusing on verification rather than earnings or listing.

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 description provides explicit guidance on when to use the tool: 'Use after they have published their verification token at /.well-known/paygate-verify on the server's domain.' It also mentions a prerequisite ('Requires the api_key from register_server'). However, it does not mention when not to use the tool or suggest alternatives, so it doesn't fully meet the 'when-not/alternatives' criterion.

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