MCPFax Bazaar Intelligence

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the agent knows this is a safe read. The description adds pricing ($0.005 per successful call) and the notion of success-based billing, which is useful. However, it does not disclose output format, pagination, or any other behavioral traits beyond what annotations provide.

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 very short and includes the price, with no wasted words. However, the phrasing is a dependent clause rather than a clear imperative, and the core function is somewhat buried in metaphor. Still, it is concise and readable.

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 has one optional parameter, strong annotations, and no output schema, the description should at least hint at the return shape. It only describes the concept and price, not what the response contains or how the category filter affects it. It is adequate for a simple read-only query 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%: the single optional 'category' parameter has an enum and a clear 'Optional deterministic category filter' description. The tool description adds nothing about the parameter, but the schema carries the full semantic weight, so baseline 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, 'Where agents are spending and almost nobody is selling — demand against classified supply', is evocative but does not specify an explicit verb or resource name. It implies the tool surfaces category-level demand/supply gaps, but never directly says 'returns' or 'lists'. This is clearer than a pure tautology but still vague about the exact operation.

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?

No guidance is provided about when to use this tool versus the named siblings (market_report, new_entrants, seller_rank, top_movers, trending_services). The description does not mention alternatives, exclusions, or preferred contexts.

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?

Although annotations already declare read-only, idempotent, and non-destructive behavior, the description adds valuable details beyond them: the price per successful call, the promised observation window, and the condition under which concentration adjustments are or are not applied. These are behavioral nuances an agent needs before calling.

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 sentences, each earning its place: the first enumerates the report's content, the second provides a data-quality caveat, and the third states the price and the free alternative. No filler words, and the key facts are front-loaded.

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 simple zero-argument, zero-output-schema report, the description is complete. It tells an agent what the report contains, its edge case (scan coverage), its price, and how it differs from related free content. Nothing essential is missing for correctly calling and using this tool.

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 has no parameters (empty input schema, 0 required params), so the description does not need to elaborate on parameter meaning. Zero-parameter tools get a baseline of 4; the description appropriately explains the payload this no-argument call returns.

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 role: a daily report on the x402 agent economy covering USDC inflow, seller ranking, category demand, growth, and coverage. It also distinguishes itself from the free market_digest by emphasizing that this is for derived figures rather than mere changes.

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 positions the tool against a comparable alternative: 'a FREE register-wide change digest... is market_digest on the x402-observatory gateway; buy this for the derived figures, not for what merely changed.' This gives clear guidance on selecting this paid report over a free sibling.

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 mark this as read-only and idempotent, and the description adds valuable behavioral details: a 422 refusal with no charge for empty windows, partial coverage before the archive's first date, and per-call pricing. No contradiction with annotations exists.

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 information-dense with no filler; every sentence contributes to selection, invocation, or cost understanding. The middle sentence on attribution is slightly convoluted, but overall it is appropriately sized and well-structured.

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 tool with no output schema, the description gives a useful sense of what rows contain—attribution type, first archive observation, and early-traction evidence—and covers error behavior. It stops short of specifying the full return shape, but the essential selection and invocation context is present.

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 input schema already documents both parameters completely, so baseline is 3. The description references a date and window indirectly but does not add meaningful parameter-specific semantics beyond 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 clearly states the tool lists x402 services first listed since a given date, with first archive observation and early-traction evidence. It also defines the attribution model and row content, which distinguishes it from the sibling analytics 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 opening clause establishes a clear use case: finding services newly listed since a date. It does not explicitly contrast with sibling tools like x402_trending_services or x402_top_movers, but the unique purpose and sibling names make the distinction reasonably clear.

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 cover read-only, idempotent, and non-destructive behavior. The description adds valuable context beyond those annotations: the per-call price and the fact that data is read off Base. No contradiction with 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 terse, purposeful sentences: the first states the core value and distinguishing qualifier, the second states essential pricing. No filler, no redundant restatement of the title, and the most important information is upfront.

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 simple read-only list tool with optional parameters and full schema coverage, the description gives sufficient context: what is being ranked, by which metric, and at what cost. The absence of an output schema makes the lack of return-row details a minor gap, but not enough to lower the overall completeness significantly.

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. Both parameters (limit and category) are fully documented in the input schema, and the description itself adds no extra parameter semantics. The baseline applies correctly.

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 names a specific resource (x402 sellers), an action (rank), and the basis (USDC read off Base). It also distinguishes the tool from self-reported claims, which helps an agent tell it apart from sibling tools that likely handle demand, trends, or new entrants.

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 implies when to use it (when objective on-chain earnings are needed rather than self-reported figures) but does not explicitly name alternatives or state when not to use it. The sibling context is external, and the description itself fails to guide the agent toward or away from other tools.

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 cover read-only, idempotent, and non-destructive behavior. The description adds valuable operational context beyond those annotations: the call costs $0.01 USDC per successful call and the data is specifically pre-ranking movers. This is useful but does not fully describe response 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?

Two short sentences carry distinct information: what the tool surfaces and its per-call price. There is no filler, and the core concept is front-loaded.

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, no-required-input, heavily annotated read tool, the description conveys the core data type, its timing advantage, and the pricing constraint. It does not describe the output shape, but with no output schema and low complexity this 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?

The single `limit` parameter is already fully documented in the schema with min, max, default, and a description. The tool description adds no additional parameter meaning, so baseline 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 names a specific subject: sudden inflow spikes and first-seen large payers, and frames the tool as an early pre-ranking signal. It also differentiates from the general ranking-type siblings. However, it is a noun phrase rather than an explicit verb+resource statement like 'Returns...' or 'Lists...', so it stops short of a 5.

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 phrase 'before they show up in a ranking' implies this is for early detection of movers, but the description does not explicitly state when to use this tool over x402_new_entrants or x402_trending_services. Sibling differentiation is left mostly to inference.

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, idempotentHint, and destructiveHint false. The description adds value beyond that by disclosing the cost ($0.01 USDC per successful call) and the methodology (inflow across comparable windows). It doesn't detail response format or failure behavior, but the annotation coverage lowers the burden.

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 short sentences: the first states the core purpose with a specific metric, the second states pricing. No filler or redundant terms.

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 simple, one-optional-parameter read-only tool, the description covers the core behavior and cost. It does not describe the output shape, and there is no output schema, but the name and purpose imply a list of services. Slight ambiguity around 'comparable windows' remains, but overall sufficient.

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 single `limit` parameter is 100% documented in the schema with min, max, default, and description. The tool description adds no parameter-specific detail, so the baseline 3 applies.

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 resource (x402 services) and the selection criterion (growing now by observed inflow across comparable windows). It avoids tautology and gives a specific measurement basis. It lacks an explicit imperative verb like 'list' or 'return', which keeps it from a 5.

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?

No guidance on when to use this tool versus siblings like x402_top_movers or x402_new_entrants. The description explains what it does but not when it should be preferred, nor does it name alternatives or exclusions.

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