catalogFree. Start here: every tool with its price, arguments and x402 payment terms (USDC on Solana or Base), plus the label semantics URL. Use it first to choose a tool and budget; it carries no market data.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
| ok | No | ||
| data | No | ||
| meta | No | ||
| coverage | No |
Changes observed during successful MCP inspections.
Output schema / (root)Previous value: -nullNew value: +{
+ "properties": {
+ "coverage": {
+ "type": "string"
+ },
+ "data": {
+ "type": [
+ "object",
+ "null"
+ ]
+ },
+ "meta": {
+ "type": "object"
+ },
+ "ok": {
+ "type": "boolean"
+ }
+ },
+ "type": "object"
+}Output schema / (root)Previous value: -{
- "anyOf": [
- {
- "properties": {
- "coverage": {
- "enum": [
- "full",
- "thin"
- ]
- },
- "data": {
- "properties": {
- "docs": {
- "type": "object"
- },
- "free_tools": {
- "items": {
- "type": "string"
- },
- "type": "array"
- },
- "labels": {
- "type": "object"
- },
- "payment": {
- "type": "object"
- },
- "source": {
- "type": "object"
- },
- "tools": {
- "items": {
- "type": "object"
- },
- "type": "array"
- }
- },
- "required": [
- "tools",
- "free_tools",
- "payment"
- ],
- "type": "object"
- },
- "meta": {
- "type": "object"
- },
- "ok": {
- "const": true
- }
- },
- "required": [
- "ok",
- "schema_version",
- "generated_at",
- "t",
- "coverage",
- "data",
- "meta"
- ],
- "type": "object"
- },
- {
- "properties": {
- "error": {
- "type": "string"
- },
- "ok": {
- "const": false
- }
- },
- "required": [
- "ok",
- "error"
- ],
- "type": "object"
- }
- ],
- "type": "object"
-}New value: +nullInput schema / titleRemoved value: -"catalogArguments"Output schema / anyOfPrevious value: -[
- {
- "properties": {
- "coverage": {
- "enum": [
- "full",
- "thin"
- ]
- },
- "data": {
- "properties": {
- "docs": {
- "type": "object"
- },
- "free_tools": {
- "items": {
- "type": "string"
- },
- "type": "array"
- },
- "labels": {
- "type": "object"
- },
- "payment": {
- "type": "object"
- },
- "source": {
- "type": "object"
- },
- "tools": {
- "items": {
- "type": "object"
- },
- "type": "array"
- }
- },
- "required": [
- "tools",
- "free_tools",
- "payment"
- ],
- "type": "object"
- },
- "generated_at": {
- "type": "string"
- },
- "meta": {
- "properties": {
- "feed_lag_s": {
- "type": [
- "number",
- "null"
- ]
- },
- "is_stale": {
- "type": "boolean"
- }
- },
- "type": "object"
- },
- "ok": {
- "const": true
- },
- "schema_version": {
- "type": "string"
- },
- "t": {
- "type": "number"
- }
- },
- "required": [
- "ok",
- "schema_version",
- "generated_at",
- "t",
- "coverage",
- "data",
- "meta"
- ],
- "title": "Catalog",
- "type": "object"
- },
- {
- "description": "isError: the x402 v2 payment requirements. Pay one accepts entry and call again with _meta['x402/payment']. error says why when a payment was sent and rejected; a failed settlement adds x402/payment-response. Nothing is charged.",
- "properties": {
- "accepts": {
- "items": {
- "properties": {
- "amount": {
- "type": "string"
- },
- "asset": {
- "type": "string"
- },
- "extra": {
- "type": "object"
- },
- "maxTimeoutSeconds": {
- "type": "integer"
- },
- "network": {
- "type": "string"
- },
- "payTo": {
- "type": "string"
- },
- "scheme": {
- "type": "string"
- }
- },
- "required": [
- "scheme",
- "network",
- "amount",
- "asset",
- "payTo"
- ],
- "type": "object"
- },
- "minItems": 1,
- "type": "array"
- },
- "error": {
- "type": "string"
- },
- "extensions": {
- "type": "object"
- },
- "resource": {
- "properties": {
- "description": {
- "type": "string"
- },
- "mimeType": {
- "type": "string"
- },
- "url": {
- "type": "string"
- }
- },
- "required": [
- "url"
- ],
- "type": "object"
- },
- "x402/payment-response": {
- "properties": {
- "errorReason": {
- "type": "string"
- },
- "network": {
- "type": "string"
- },
- "success": {
- "type": "boolean"
- },
- "transaction": {
- "type": "string"
- }
- },
- "required": [
- "success"
- ],
- "type": "object"
- },
- "x402Version": {
- "const": 2
- }
- },
- "required": [
- "x402Version",
- "resource",
- "accepts"
- ],
- "title": "PaymentRequired",
- "type": "object"
- },
- {
- "description": "isError: a refusal answered without charging (invalid or uncovered arguments, stale feed, nothing new since the cursor, a payment that cannot be matched to this request). error is a stable code; live_examples name mints covered now.",
- "properties": {
- "address": {
- "type": "string"
- },
- "avoid_skipped": {
- "type": "integer"
- },
- "case_mangled_mints": {
- "items": {
- "type": "string"
- },
- "type": "array"
- },
- "charged": {
- "type": [
- "boolean",
- "null"
- ]
- },
- "curve": {
- "type": "string"
- },
- "error": {
- "type": "string"
- },
- "feed_lag_s": {
- "type": [
- "number",
- "null"
- ]
- },
- "free_check": {
- "type": "string"
- },
- "got": {
- "type": [
- "string",
- "integer"
- ]
- },
- "hint": {
- "type": "string"
- },
- "invalid": {
- "type": "object"
- },
- "live_examples": {
- "items": {
- "type": "string"
- },
- "type": "array"
- },
- "max_feed_lag_s": {
- "type": "number"
- },
- "max_mints": {
- "type": "integer"
- },
- "max_table_lag_s": {
- "type": "number"
- },
- "message": {
- "type": "string"
- },
- "mint": {
- "type": "string"
- },
- "missing": {
- "items": {
- "type": "string"
- },
- "type": "array"
- },
- "newest_cursor": {
- "type": "string"
- },
- "ok": {
- "const": false
- },
- "payment_status": {
- "type": "string"
- },
- "scanned": {
- "type": "integer"
- },
- "schema": {
- "type": "object"
- },
- "since": {
- "type": [
- "string",
- "null"
- ]
- },
- "table_lag_s": {
- "type": [
- "number",
- "null"
- ]
- },
- "tool": {
- "type": "string"
- },
- "unavailable_mints": {
- "items": {
- "type": "string"
- },
- "type": "array"
- },
- "unverified_event": {
- "type": [
- "object",
- "null"
- ]
- },
- "window_s": {
- "type": "number"
- }
- },
- "required": [
- "ok",
- "error"
- ],
- "title": "Refusal",
- "type": "object"
- }
-]New value: +[
+ {
+ "properties": {
+ "coverage": {
+ "enum": [
+ "full",
+ "thin"
+ ]
+ },
+ "data": {
+ "properties": {
+ "docs": {
+ "type": "object"
+ },
+ "free_tools": {
+ "items": {
+ "type": "string"
+ },
+ "type": "array"
+ },
+ "labels": {
+ "type": "object"
+ },
+ "payment": {
+ "type": "object"
+ },
+ "source": {
+ "type": "object"
+ },
+ "tools": {
+ "items": {
+ "type": "object"
+ },
+ "type": "array"
+ }
+ },
+ "required": [
+ "tools",
+ "free_tools",
+ "payment"
+ ],
+ "type": "object"
+ },
+ "meta": {
+ "type": "object"
+ },
+ "ok": {
+ "const": true
+ }
+ },
+ "required": [
+ "ok",
+ "schema_version",
+ "generated_at",
+ "t",
+ "coverage",
+ "data",
+ "meta"
+ ],
+ "type": "object"
+ },
+ {
+ "properties": {
+ "error": {
+ "type": "string"
+ },
+ "ok": {
+ "const": false
+ }
+ },
+ "required": [
+ "ok",
+ "error"
+ ],
+ "type": "object"
+ }
+]Output schema / descriptionRemoved value: -"One of three shapes. Success (isError false): the JSON envelope {ok, schema_version, generated_at, t, coverage, data, meta}. isError true: the x402 PaymentRequired {x402Version 2, resource, accepts[, error]} (pay and call again) or a refusal {ok: false, error, message, charged: false}; neither is charged."Output schema / (root)Previous value: -nullNew value: +{
+ "anyOf": [
+ {
+ "properties": {
+ "coverage": {
+ "enum": [
+ "full",
+ "thin"
+ ]
+ },
+ "data": {
+ "properties": {
+ "docs": {
+ "type": "object"
+ },
+ "free_tools": {
+ "items": {
+ "type": "string"
+ },
+ "type": "array"
+ },
+ "labels": {
+ "type": "object"
+ },
+ "payment": {
+ "type": "object"
+ },
+ "source": {
+ "type": "object"
+ },
+ "tools": {
+ "items": {
+ "type": "object"
+ },
+ "type": "array"
+ }
+ },
+ "required": [
+ "tools",
+ "free_tools",
+ "payment"
+ ],
+ "type": "object"
+ },
+ "generated_at": {
+ "type": "string"
+ },
+ "meta": {
+ "properties": {
+ "feed_lag_s": {
+ "type": [
+ "number",
+ "null"
+ ]
+ },
+ "is_stale": {
+ "type": "boolean"
+ }
+ },
+ "type": "object"
+ },
+ "ok": {
+ "const": true
+ },
+ "schema_version": {
+ "type": "string"
+ },
+ "t": {
+ "type": "number"
+ }
+ },
+ "required": [
+ "ok",
+ "schema_version",
+ "generated_at",
+ "t",
+ "coverage",
+ "data",
+ "meta"
+ ],
+ "title": "Catalog",
+ "type": "object"
+ },
+ {
+ "description": "isError: the x402 v2 payment requirements. Pay one accepts entry and call again with _meta['x402/payment']. error says why when a payment was sent and rejected; a failed settlement adds x402/payment-response. Nothing is charged.",
+ "properties": {
+ "accepts": {
+ "items": {
+ "properties": {
+ "amount": {
+ "type": "string"
+ },
+ "asset": {
+ "type": "string"
+ },
+ "extra": {
+ "type": "object"
+ },
+ "maxTimeoutSeconds": {
+ "type": "integer"
+ },
+ "network": {
+ "type": "string"
+ },
+ "payTo": {
+ "type": "string"
+ },
+ "scheme": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "scheme",
+ "network",
+ "amount",
+ "asset",
+ "payTo"
+ ],
+ "type": "object"
+ },
+ "minItems": 1,
+ "type": "array"
+ },
+ "error": {
+ "type": "string"
+ },
+ "extensions": {
+ "type": "object"
+ },
+ "resource": {
+ "properties": {
+ "description": {
+ "type": "string"
+ },
+ "mimeType": {
+ "type": "string"
+ },
+ "url": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "url"
+ ],
+ "type": "object"
+ },
+ "x402/payment-response": {
+ "properties": {
+ "errorReason": {
+ "type": "string"
+ },
+ "network": {
+ "type": "string"
+ },
+ "success": {
+ "type": "boolean"
+ },
+ "transaction": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "success"
+ ],
+ "type": "object"
+ },
+ "x402Version": {
+ "const": 2
+ }
+ },
+ "required": [
+ "x402Version",
+ "resource",
+ "accepts"
+ ],
+ "title": "PaymentRequired",
+ "type": "object"
+ },
+ {
+ "description": "isError: a refusal answered without charging (invalid or uncovered arguments, stale feed, nothing new since the cursor, a payment that cannot be matched to this request). error is a stable code; live_examples name mints covered now.",
+ "properties": {
+ "address": {
+ "type": "string"
+ },
+ "avoid_skipped": {
+ "type": "integer"
+ },
+ "case_mangled_mints": {
+ "items": {
+ "type": "string"
+ },
+ "type": "array"
+ },
+ "charged": {
+ "type": [
+ "boolean",
+ "null"
+ ]
+ },
+ "curve": {
+ "type": "string"
+ },
+ "error": {
+ "type": "string"
+ },
+ "feed_lag_s": {
+ "type": [
+ "number",
+ "null"
+ ]
+ },
+ "free_check": {
+ "type": "string"
+ },
+ "got": {
+ "type": [
+ "string",
+ "integer"
+ ]
+ },
+ "hint": {
+ "type": "string"
+ },
+ "invalid": {
+ "type": "object"
+ },
+ "live_examples": {
+ "items": {
+ "type": "string"
+ },
+ "type": "array"
+ },
+ "max_feed_lag_s": {
+ "type": "number"
+ },
+ "max_mints": {
+ "type": "integer"
+ },
+ "max_table_lag_s": {
+ "type": "number"
+ },
+ "message": {
+ "type": "string"
+ },
+ "mint": {
+ "type": "string"
+ },
+ "missing": {
+ "items": {
+ "type": "string"
+ },
+ "type": "array"
+ },
+ "newest_cursor": {
+ "type": "string"
+ },
+ "ok": {
+ "const": false
+ },
+ "payment_status": {
+ "type": "string"
+ },
+ "scanned": {
+ "type": "integer"
+ },
+ "schema": {
+ "type": "object"
+ },
+ "since": {
+ "type": [
+ "string",
+ "null"
+ ]
+ },
+ "table_lag_s": {
+ "type": [
+ "number",
+ "null"
+ ]
+ },
+ "tool": {
+ "type": "string"
+ },
+ "unavailable_mints": {
+ "items": {
+ "type": "string"
+ },
+ "type": "array"
+ },
+ "unverified_event": {
+ "type": [
+ "object",
+ "null"
+ ]
+ },
+ "window_s": {
+ "type": "number"
+ }
+ },
+ "required": [
+ "ok",
+ "error"
+ ],
+ "title": "Refusal",
+ "type": "object"
+ }
+ ],
+ "description": "One of three shapes. Success (isError false): the JSON envelope {ok, schema_version, generated_at, t, coverage, data, meta}. isError true: the x402 PaymentRequired {x402Version 2, resource, accepts[, error]} (pay and call again) or a refusal {ok: false, error, message, charged: false}; neither is charged.",
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover safety (readOnly, idempotent, non-destructive). The description adds useful context: it is free, contains payment terms in USDC on Solana or Base, and carries no market data. It does not detail rate limits or auth, but none are evident for a free catalog.
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 'Free. Start here,' and every phrase adds value. No redundancy or wasted space.
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?
Complete for a parameterless catalog: it names the contents, payment context, and explicitly says no market data. An output schema exists, so return structure need not be explained.
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 zero parameters, so the schema description baseline is 4. The description correctly focuses on what the tool returns rather than parameter semantics, and no parameter meaning is missing.
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 it is a catalog of every tool with price, arguments, and x402 payment terms, and explicitly distinguishes itself from market-data siblings ('carries no market data'). An agent can tell it apart from all sibling tools without opening schemas.
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 instructs to use it first for choosing a tool and budget, and states it carries no market data, preventing misuse. It does not name a specific alternative, but instead routes the agent across the whole catalog.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.