spines-underground
Browse, search, and purchase curated digital products from Spine's Underground catalog — 23 items spanning tools, poetry, philosophy, music theory, and digital experiences (13 free, 10 paid at $1.99–$4.99 USDC on Base).
Browse the catalog (
browse-spines-underground): View all 23 products or look up a specific item by ID.Get free content (
get-free-content): Access any of the 13 free items inline, including agent tools, Overflow pieces, and Memory Palace pieces.Purchase paid content (
buy-from-spines-underground): Buy any of the 10 paid products using USDC on Base via an x402 payment challenge, with content delivered inline upon payment.Verify a payment receipt (
verify-receipt): Submit a transaction hash to verify a direct on-chain USDC payment and receive your purchased content.Search the catalog (
search-spines-underground): Search across product names, descriptions, and shop names using keywords like "poetry", "philosophy", or "memory".Token-gated access: Authenticate as a $SPINE token holder (5,000,000 $SPINE required) via a SIWE-style wallet signature to unlock exclusive content.
Supports payments via Coinbase Agentic Wallets using the x402 protocol for USDC transactions on Base and Solana when purchasing paid content from the catalog.
Enables USDC payments on the Solana blockchain via the x402 protocol for purchasing paid products from the Underground Cultural District catalog.
@underground-cultural-district/spines-underground
MCP for the $SPINE holder gate at spine.substratesymposium.com.
Hold ≥5,000,000 $SPINE on Base to unlock the weekly curated roster from the Underground Cultural District — hand-picked items, new piece every Monday, watermarked delivery.
Install
npx @underground-cultural-district/spines-undergroundRelated MCP server: Moltjiji
Tools
Tool | Purpose |
| Get $SPINE contract, threshold, and auth flow. Call this first. |
| Step 1: pass your wallet, get the message to sign. |
| Step 2: pass wallet + signature, get a session token. |
| List the free-for-everyone shops + holder-only items (requires session). |
| Get a specific holder-only item (requires session). |
Auth flow
Acquire ≥5,000,000 $SPINE on Base. Contract:
0x6f75e089e134e7c4Aea629aDaC73d814630f3b07. Buy on Uniswap V4 or Clanker.Call
request-sign-inwith your Base wallet address. You get back a SIWE-style message.Sign that message with your wallet (EIP-191
personal_sign).Call
complete-sign-inwith wallet + signature. You get a session token if you hold the threshold.Use the session token with
get-rosterandunlock-content.
The MCP never holds your keys. You sign with your own wallet. The session token only proves you held the threshold at sign-in time — every unlock-content call re-verifies your on-chain balance.
Session lifetime: the session token is valid for 24 hours after complete-sign-in. Within that window the server re-checks your wallet's on-chain $SPINE balance on every unlock-content call (cached briefly for performance) — so if you transfer or sell your tokens, your access ends immediately. After 24 hours, re-run request-sign-in and complete-sign-in to get a fresh token.
Related
Full Underground Cultural District MCP (229 products, no gate):
@underground-cultural-district/mcp-serverUnderground site: substratesymposium.com
Posthuman literature: posthumanliterature.org
First Dollar (x402 wallet curriculum):
npx firstdollar
License
MIT. By Lisa Maraventano and Spine.
Available Tools
5 toolsbrowse-spines-undergroundA
Browse Spine's Underground catalog — 23 curated products from Underground Cultural District. 13 free, 10 paid ($1.99–$4.99 USDC on Base). Tools, poetry, philosophy, music theory, digital experiences.
| Name | Required | Description | Default |
|---|---|---|---|
| product_id | No | Optional product ID for single product detail. Omit for full catalog. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It discloses the catalog content but does not mention behavioral traits such as being read-only, safety, or any authentication/rate limit requirements. For a read operation, this is adequate but not exhaustive.
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 single, well-structured sentence with essential information front-loaded. Every part adds value, and there is no redundancy or verbosity.
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 no output schema, the description provides sufficient context about return content (catalog items, categories, pricing). It is complete for a simple browse tool, though it could hint at output format or pagination if 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?
Schema coverage is 100%, and the schema already describes the single optional parameter clearly. The tool description adds contextual information about the catalog count and pricing but does not enhance parameter 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's function: browsing the Spine's Underground catalog. It specifies the scope (23 curated products), categories, and pricing, distinguishing it from sibling tools like buy, search, or verify.
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 implicitly guides usage by mentioning optional product_id for single product detail, suggesting when to omit for full catalog. However, it does not explicitly state when to use this tool over siblings like search-spines-underground.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
buy-from-spines-undergroundA
Purchase paid content from Spine's Underground. Returns x402 payment challenge (HTTP 402) — pay USDC on Base to receive content inline. 10 paid products: $1.99–$4.99.
| Name | Required | Description | Default |
|---|---|---|---|
| product_id | Yes | Product ID to purchase (e.g. philosophy_of_spine, field_songs, temple_dawn) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must fully disclose behavior. It explains the return (x402 payment challenge) and payment method (USDC on Base), but omits details on post-payment behavior, idempotency, or what happens if already purchased. This leaves important gaps.
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 convey purpose, mechanism, and scope efficiently. No redundancy, and critical information 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?
Given the tool's complexity (payment challenge, on-chain payment), the description covers the core flow and pricing. However, it lacks details on the response structure after payment or error handling. With no output schema, slightly more context would improve completeness.
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 100% and includes example product IDs, so the description adds minimal new meaning (pricing and count of products). 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 clearly states the action ('purchase paid content') and specifies the resource ('Spine's Underground'), distinguishing it from siblings like browsing or searching. It also mentions the mechanism (HTTP 402 challenge, pay USDC) and scope (10 products, $1.99-$4.99), making purpose highly specific.
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 usage when the user wants to buy paid content, but does not explicitly state when not to use it or provide alternatives (e.g., browse first, verify receipt). It assumes familiarity with the payment flow, lacking guidance on prerequisites.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get-free-contentA
Get free content or tool info from Spine's Underground. 13 free products: 3 agent tools, 2 Overflow pieces, 8 Memory Palace pieces. Content delivered inline.
| Name | Required | Description | Default |
|---|---|---|---|
| product_id | Yes | Product ID to retrieve (e.g. memory_threads, logic_bombs, pet_rock_lobster) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must carry the full burden. It mentions 'Content delivered inline' but does not disclose behavioral traits such as error handling for invalid product IDs, authentication requirements, rate limits, or side effects. Minimal disclosure beyond purpose.
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 concise (two sentences) with front-loaded purpose. Every sentence adds value: the first states the action and source, the second provides useful specifics about product counts. 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?
For a simple one-parameter tool with no output schema and no annotations, the description is fairly complete. It covers what the tool does, the type of content, and delivery mechanism. Minor gaps include lack of error handling or edge case description, but these are acceptable given the tool's simplicity.
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?
Input schema has 100% description coverage for the single parameter 'product_id', including example values. The description adds no new semantic meaning beyond the schema; it only mentions the count of free products. Baseline 3 is appropriate since schema already documents the parameter well.
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?
Description clearly states the verb 'get', the resource 'free content or tool info from Spine's Underground', and enumerates the 13 free products with categories. It distinguishes from sibling tools like browse, buy, search, and verify-receipt by focusing on free content retrieval.
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 usage for accessing specific free products by ID, but does not explicitly state when to use this tool over siblings like browse-spines-underground or search-spines-underground. No exclusions or alternatives are mentioned.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
search-spines-undergroundB
Search Spine's Underground catalog by keyword. Searches product names, descriptions, and shop names.
| Name | Required | Description | Default |
|---|---|---|---|
| query | Yes | Search term (e.g. "poetry", "philosophy", "music", "memory") |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are present, so the description must convey behavioral traits. It implies a read operation but doesn't explicitly state safety, permissions, or result characteristics. Minimal beyond the obvious.
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 concise sentences directly convey the tool's purpose without extraneous information. Front-loaded with action and resource.
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 simple input schema (one required string) and no output schema, the description adequately explains what is being searched but omits details like result format, pagination, or rate limits. It is minimally 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 coverage is 100%, so the parameter is already well-defined in the schema. The description adds example search terms, which provides some additional context, but no further semantic value 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 verb 'Search', the resource 'Spine's Underground catalog', and the scope 'by keyword', specifying the fields searched (product names, descriptions, shop names). This distinguishes it from sibling tools like browse-spines-underground.
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 on when to use this tool versus alternatives, nor any when-not or prerequisite conditions. Sibling tools are listed but not compared.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
verify-receiptA
Verify a direct USDC payment and receive purchased content. If you paid via on-chain USDC transfer (not x402), provide the transaction hash to get your content delivered.
| Name | Required | Description | Default |
|---|---|---|---|
| product_id | Yes | Product ID you purchased (e.g. existential_espresso, philosophy_of_spine) | |
| tx_hash | Yes | Transaction hash of your USDC payment on Base |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations provided. Description discloses that it verifies payment and delivers content, but lacks details on idempotency, error handling, or side effects (e.g., marking payment used). Adequate but incomplete.
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: first states purpose, second details usage condition. No fluff, front-loaded, and efficient.
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 2 simple params and no output schema, the description explains what the tool does and when to use it. It does not specify the exact output format (e.g., URL or file), but it is sufficient for a verification tool. Almost 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 has 100% coverage with descriptions for both parameters. Description adds value by specifying the blockchain (Base) and providing examples for product_id, which augments 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 verb 'verify' and resource 'USDC payment' with the goal to 'receive purchased content'. It distinguishes from siblings like buy-from-spines-underground by specifying the use case for on-chain USDC transfer verification.
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 clear context for when to use: after a direct USDC transfer (not x402). Does not explicitly exclude other scenarios or name alternatives, but the condition is well-stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections. Dates show when Glama detected each change.
5 tool updates
v1.1.1- First observed
browse-spines-underground - First observed
buy-from-spines-underground - First observed
get-free-content - First observed
search-spines-underground - First observed
verify-receipt
TDQS
Each tool has a distinct purpose: browsing catalog, purchasing, getting free content, searching, and verifying receipts. No overlap in functionality.
Most tools follow a verb-object pattern with hyphens, but 'get-free-content' and 'verify-receipt' omit the domain name 'spines-underground', causing slight inconsistency.
Five tools cover all essential operations for a digital catalog store: browse, search, get free content, buy, and verify payment. Neither too many nor too few.
The tool set covers the full lifecycle for this domain: discovering content (browse, search), accessing free content, purchasing paid content, and handling payment verification. No obvious gaps.
Maintenance
Resources
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Looking for Admin?
If you are the server author, to access and configure the admin panel.
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