MCPFax Bazaar Intelligence

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

Annotations already establish read-only and idempotent behavior; the description adds the pricing model ($0.005 per successful call) and frames the output as a demand-vs-supply classification, which goes beyond annotation defaults. It doesn't mention rate limits or error behavior, but the low bar is met.

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 clauses and a price line — no waste. The metaphor is compact though arguably cryptic; still, it conveys the core value in few 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?

For a one-optional-param read-only tool, the safe profile is covered by annotations and the conceptual output is stated. However, without an output schema, the description leaves the exact response shape implied ('demand against classified supply') rather than specified, so an agent doesn't know precisely what fields to expect.

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 covers the only parameter 100% with enum and description, so the description adds no parameter-specific information. Baseline 3 is appropriate because the schema does the heavy lifting.

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 phrase 'demand against classified supply' conveys a specific lens (high spending, low selling) and the title/subject is category demand. It is not a tautology and conceptually distinguishes from sibling market metrics like rankings or movers, though it never names them.

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 the use case — identifying underserved categories — but gives no explicit condition, exclusion, or pointer to sibling tools. The price line adds cost context but no selection guidance.

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?

Beyond the annotations, the description discloses important runtime behaviors: a window matching nobody returns 422 and is not charged, requests before the archive's first date are only partially covered, and each call costs $0.01 USDC on success. It also explains the attribution ranking logic, giving the agent a clear model of what the tool does and what happens on edge cases.

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 dense but well-organized: the core purpose comes first, followed by attribution logic, then failure behavior and cost. Every sentence adds distinct information, and there is no filler 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 description covers the tool's purpose, row-level attribution meaning, failure modes, pricing, and coverage limits, which is substantial for a read-only tool with only two optional parameters. It does not enumerate every possible row field, but the absence of an output schema is partially mitigated by the explicit statement that each row indicates which attribution it carries.

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 parameters limit and since are already fully documented in the schema. The description reinforces the meaning of 'since' by framing it as services first listed after a given date, but it does not add materially new parameter-level meaning 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 identifies the resource (x402 services first listed since a date) and the specific lens: early-traction evidence from observed inflow. It further distinguishes itself by explaining how attributed entrants rank first and that each row indicates which attribution signal it carries, separating it from sibling trend and ranking 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 gives a clear use context: discovering x402 services first listed since a date, with attribution and inflow evidence. It does not explicitly name alternatives or state when to prefer another sibling tool, but the focus on newly listed entrants is specific enough for an agent to select it appropriately.

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?

Beyond the readOnlyHint/idempotentHint annotations, the description discloses that the call costs $0.01 USDC and appears to charge only on success, which is material behavioral information. It also clarifies that the data comes from on-chain Base USDC activity rather than seller claims.

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 long, leads with the core ranking purpose, and the second sentence adds the pricing caveat. There is no filler or repeated schema 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 low-complexity read-only tool with no required parameters, the description covers what is ranked, the data source, and the cost. It omits the exact return shape, but an agent can infer a ranked seller list from 'Which x402 sellers actually earn, ranked by...'.

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%, and the schema already documents limit and category clearly, including defaults and range/enum constraints. The tool description adds no parameter-level meaning, 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 names the resource ('x402 sellers') and the ranking basis ('USDC read off Base — not by their own claims'), giving a specific, actionable purpose. The phrase 'ranked by USDC' also distinguishes this tool from sibling tools like x402_trending_services or x402_category_demand.

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 gives no guidance on when to choose this tool over x402_market_report, x402_top_movers, or the other siblings. It does not state use cases, exclusions, or conditions under which another tool would be preferable.

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=true and idempotentHint=true, so the safe read-only nature is covered without needing restatement. The description adds a critical behavioral fact: each successful call costs $0.01 USDC, which an agent must know before invoking the tool. It also clarifies that the output is early signals rather than final ranking data, and it does not contradict 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 short sentences with no filler or redundant phrasing. The value proposition is front-loaded, and the pricing note is appended compactly. Every word contributes to the agent's understanding of what the tool does and what it costs.

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 read-only tool with one optional parameter and strong annotations, the description provides enough context for selection and invocation. It covers the core output concept, the early-signal positioning, and the cost per call, while the schema handles the limit parameter. It does not specify time window, ordering, or exact output shape, which keeps it just short of 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?

The only parameter, limit, is fully documented in the input schema with its default, minimum, maximum, and meaning, giving 100% schema coverage. The description adds no parameter-specific details, but the schema already provides everything needed. This matches the baseline for a fully documented single parameter.

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 indicates that the tool surfaces sudden inflow spikes and first-seen large payers, positioning these as early signals before they appear in rankings. It lacks an explicit verb like 'lists' or 'returns', so it is a noun-phrase description rather than a full purpose statement. It partially distinguishes from rankings but does not name sibling 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 phrase 'before they show up in a ranking' implies a use case around early detection of movers, which provides some contextual guidance. However, there are no explicit when-to-use instructions, exclusions, or named alternatives among the sibling tools. An agent must infer when to choose this over x402_new_entrants or x402_trending_services.

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, so the safety profile is covered. The description adds meaningful extras: the pricing model ('$0.01 USDC per successful call') and the methodology ('observed inflow across comparable windows'), which goes 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 compact and front-loaded: the first sentence states the core purpose and measurement basis, and the second adds the cost. Every sentence earns its place without 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 minimal schema, strong annotations, and simple optional limit parameter, the description is nearly sufficient. It does not state the output shape or fields (e.g., service names, inflow deltas), but for a simple read-only trending query with one optional parameter, the missing return details are not critical for invoking 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 description coverage is 100%, and the single 'limit' parameter is fully documented with type, range, default, and example. The description does not add parameter-specific meaning, but the schema already carries the burden, so the baseline score 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 clearly identifies the tool as a way to find x402 services that are growing by observed inflow across comparable windows. It conveys the resource and the specific angle ('growing right now'), though it does not explicitly distinguish itself from sibling tools like x402_top_movers or x402_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?

No explicit guidance is given about when to choose this tool over the listed siblings. The phrase 'growing right now' implies a use case, but the description never states alternatives, exclusions, or conditions that would help an agent decide between x402_trending_services and x402_top_movers or x402_new_entrants.

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