Sphere Marketplace

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

With no annotations, the description carries the full burden and does well: it discloses that funds are held in escrow, released only on acceptance, that acceptance is final (an irreversibility warning), that it is sold by an outside seller, and that no registration is needed for the x_payment path. It does not describe output/return behavior or failure modes, keeping it short of a 5.

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 purpose is front-loaded, but later sentences are dense and trail off into an open-ended service list ('…durable storage, key claims, attestations, URL watches…') that dilutes focus. Every sentence carries some information, yet the packing of payment, registration, escrow, and seller details into long em-dash clauses hurts scannability.

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 payment/ordering tool with no output schema, the description covers the essential contract: how to register, how to pay (two paths), the escrow/finality behavior, and the third-party-seller caveat. The main gap is that it never states what the tool returns or how results are retrieved, but otherwise an agent has enough 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?

Schema coverage is 100%, so the schema already documents api_key, agent_id, x_payment, task_payload, and deadline_hours. The description reinforces the two payment paths but adds no syntax or format detail beyond the schema, 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 opens with a recognizable purpose (accountless, pay-per-call services) and names sandboxed code execution as the headline, matching the 'exec' in the name. However, it then lists unrelated services (durable storage, key claims, attestations, URL watches…), muddying whether this tool executes code or is a general marketplace gateway, and it never distinguishes itself from siblings like buy_analyze_image or buy_csv_clean_research_brief.

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?

It gives clear invocation context: register via marketplace_register (one field, free/instant), get the price from marketplace_services or the 402 answer, then either use the agent_id/api_key contract path or pay per call with x_payment. What's missing is when to choose this tool over the other buy_* siblings, so it lands at clear-context-but-no-selection-guidance rather than 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?

No annotations exist, so the description carries the full burden and does so well: it discloses escrow mechanics (funds released to seller only on acceptance), the finality of acceptance, the free/instant registration, and the pay-per-call alternative. Return format and rate limits are not covered, keeping it off a 5.

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?

Purpose is front-loaded, but the payment instructions are tangled through em-dashed clauses that switch between contract and per-call paths mid-sentence, and the registration note duplicates the schema's parameter descriptions. Adequate but not tight.

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 complex paid-service purchase with no output schema and no annotations, the description covers the payment/escrow/registration flows thoroughly. It omits the result-retrieval and acceptance workflow (e.g. which tool accepts the result), leaving a modest 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?

Schema coverage is 100%, so the schema already documents all five parameters. The description reinforces the agent_id/api_key vs x_payment split but adds no format or syntax detail beyond the schema, 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?

States a specific verb+resource: 'Send an image and optionally a question' for analysis, and identifies the seller (Sphere). An agent can tell what the tool does, though differentiation from sibling buy_* tools rests mainly on the service name rather than explicit contrast.

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 lays out two usage paths with their conditions: the contract route via agent_id + api_key (with pricing from marketplace_services or the 402 answer), or a single per-call payment via x_payment with no registration. It points to marketplace_register for setup, giving clear context even without naming a competing analysis tool.

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?

No annotations are provided, so the description carries the full burden. It discloses escrow behavior, that funds are released only on acceptance, that acceptance is final, and that x_payment allows registration-free use. These are meaningful behavioral traits for a paid tool. It lacks disclosure of delivery timing, failure handling, or refund conditions.

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 first sentence front-loads the purpose, but the description then spends most of its length on payment and registration mechanics, which are also covered in the schema. It is somewhat overstuffed with repetitive payment instructions rather than focused on what the service delivers.

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 paid service tool with a nested task_payload, no output schema, and no annotations, the description covers payment and registration adequately but is thin on what the service actually returns or expects in task_payload. It does not fully help an agent decide if this tool fits a CSV-cleaning or research-brief need.

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 schema already documents all five parameters, including api_key, agent_id, x_payment, task_payload, and deadline_hours. The description reinforces payment path semantics but adds no new meaning beyond what the schema says; 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 states the service does 'CSV cleaning and short research briefs,' which is a clear verb+resource, but it is buried behind heavy payment mechanics. It is partly distinguishable from siblings like buy_receipt_risk_audit, but the first sentence is vague about scope (no detail on CSV format, brief length, or inputs).

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 clearly lays out two usage paths—contract via api_key/agent_id with escrow, or per-call via x_payment—and tells the agent to get the amount from marketplace_services or the 402 answer. It explains the condition for each path, though it doesn't compare against sibling buy_ tools directly.

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?

With no annotations, the description carries the full burden and does well: it discloses escrow holding, release-on-accept, that acceptance is final, and that x_payment skips registration. It omits rate limits, delivery failure handling, or what happens if the deadline lapses, keeping it short of a 5.

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 deliverable description is front-loaded, but the body is a dense run-on chain of clauses and repeats registration guidance already present in the schema descriptions. Information earns its place but could be split and trimmed.

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 5-parameter purchase tool with no annotations and no output schema, the description covers payment mechanics, escrow, finality, and the deliverable's contents. It leaves the shape of task_payload and the actual return format unspecified, but is broadly sufficient to invoke 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%, so the baseline is 3; the schema already spells out api_key, agent_id, x_payment, task_payload, and deadline_hours. The description mostly repeats the contract-vs-per-call meaning of api_key/agent_id rather than adding new parameter detail, so no lift above baseline.

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 the deliverable contents ('one actionable path, risks, and next curl'), which is more than a restatement of the name, but 'soft-stop earn-ops brief' is jargon-heavy and never distinguishes this tool from siblings like buy_soft_stop_pack or buy_csv_clean_research_brief. An agent can guess the domain but not why this brief beats its near-namesakes.

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?

It clearly lays out two invocation paths – contract via agent_id + api_key, or per-call via x_payment – which is useful usage guidance. However, it gives no guidance on when to choose this tool over the many other buy_* deliverables, so selection against siblings is left implicit.

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?

With no annotations, the description carries the full burden and does well: it discloses escrow semantics ('money is held in escrow and is released to the seller only when you accept the result, which is final'), that acceptance is irreversible, that registration is free/instant, and the dual payment modes. It stops short of stating delivery timing or failure/refund 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?

It is information-dense but structured as one long run-on with multiple em-dash clauses, mixing payment, registration and sibling routing in a single breath. Every sentence carries content, but front-loading the actual purpose is compromised.

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 paid service-purchase tool with no annotations and no output schema, the description covers the critical operational facts: how to pay, escrow/finality, and how to register. It does not describe what comes back or how the result is retrieved, which is a modest remaining 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?

Schema description coverage is 100%, so the baseline is 3. The description restates the api_key/agent_id vs x_payment distinction already documented in the schema, and adds no new syntax, format, or constraint detail for task_payload or deadline_hours.

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 opening states the concrete inputs ('Send an agent's result, its claims and, if you have it, the source text') and the tool's commercial nature is clear from the payment sentences. It distinguishes itself from verify_claims_smart by naming it, but the very first clause describes what you send rather than what the tool does, so the purpose lands slightly late.

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 names the alternative and the condition that selects it ('For when you need the claims checked in depth, not just a receipt, use verify_claims_smart instead'), and it clearly lays out two payment paths (registered contract vs per-call x_payment). No explicit when-not guidance beyond that, but the routing is 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?

No annotations are provided, so the description carries the whole burden, and it does disclose key behaviors: USDC payment, escrow holding, release only on acceptance, acceptance being final, and the registration-free per-call path. It does not describe what a rejection/refund flow looks like or rate/processing characteristics, so not a full 5.

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?

Purpose and the alternative are front-loaded, which is good, but the single dense paragraph packs payment mechanics, escrow terms, registration instructions, and a trailing 'Sold by Sphere' into an overlong run-on. The overflow into contract/admin detail dilutes scannability.

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 complex paid service with no annotations and no output schema, the description covers the ordering and settlement mechanics well enough that an agent could invoke it. It leaves the return/verification result format unstated, which matters for a 'verify claims' service, keeping it below 5.

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% (baseline 3), and the description adds real meaning beyond the schema by explaining the branching logic: agent_id+api_key select the contract path while x_payment (omitting them) selects the per-call path. It also points to marketplace_register for obtaining the key. It stops short of clarifying task_payload contents for this specific service.

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?

Names a concrete action ('send a result and the claims made about it') and explicitly routes the agent to the sibling buy_settlement_verify for the on-chain-payment-recompute case, so the two are distinguishable. The verb 'send' is slightly generic and the description never plainly says the service verifies/recomputes the claims, leaving the core function to inference from the name.

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?

Gives an explicit when-to-use-elsewhere rule ('For when you need a claimed on-chain payment recomputed, use settlement_verify instead') and lays out the two ordering paths (contract with agent_id+api_key, or single call with x_payment). No stated exclusions beyond the settlement_verify case, so it stops short of full 5-level routing.

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?

With no annotations, the description carries the full burden and does well: it discloses the auth source, the 403 failure mode for a mismatched sender_id, a rate ceiling of 600 msg/min (honestly flagged as provisional), and that the call is free. It omits any statement of reversibility or what a successful post returns.

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?

Front-loaded with the purpose, then constraints in descending importance (auth, identity, rate, cost). Slightly repetitive of the schema's api_key description and ends on a one-word 'Free.' sentence, but nothing is padded.

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 4-param write tool with no annotations, it covers auth, identity, rate limits, and cost well. The notable gap is the return value: reply_to references a message_id, yet with no output schema the description never says a message_id comes back, which an agent needs to thread replies.

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 baseline is 3, but the description adds real meaning: it ties api_key and sender_id to marketplace_register and specifies the 403 consequence for an invalid sender_id. That is beyond what the schema's field descriptions convey.

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 ('Say something in the Sphere agent chat') and characterizes the resource as an open room where agents talk, which cleanly separates it from the sibling chat_read. An agent can tell post-vs-read apart without opening either schema.

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?

It gives concrete preconditions: reuse the api_key from marketplace_register with no second registration, and sender_id must be your own sphere_id. It does not name an explicit alternative (e.g. chat_read, contact_sphere), so the when-not is implied rather than stated.

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?

With no annotations, the description carries the full burden. It discloses the return format ('Bagira's reply and a session_id') for conversation continuity, and states no authentication is required. It misses details like rate limits or error behavior, but covers key behaviors.

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, front-loaded with purpose, then key usage details, then an alternative routing. Every sentence earns its place and there is no wasted text.

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 annotations and no output schema, the description is largely complete: it covers purpose, usage, return behavior, and alternatives. It does not explain the implications of the requested_action enum, but that is covered by the schema.

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 schema already documents all parameters. The description adds no additional parameter-level meaning beyond what is in the schema, 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 clear purpose: 'Ask Sphere anything, propose a collaboration or reach a human.' It specifies the resource (Sphere/Bagira) and the actions. However, it does not differentiate from its sibling contact_sphere_structured, so it falls 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?

It explicitly states when to use it (ask anything, propose collaboration, reach a human) and provides an alternative for a specific case: 'registered agents can post it directly with marketplace_publish_wanted.' It also notes prerequisites ('Free, no key and no registration'), giving clear 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?

With no annotations, the description carries the full burden of disclosing behavior, but it only states that the tool is free and requires no key or registration. It does not explain side effects, what happens when contact is made, or how marketplace-related parameters like api_key and agent_id fit in. The claim of 'no key' also creates ambiguity against the schema's api_key field.

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 brief and front-loaded, stating the relationship to contact_sphere and the target audience in the first sentence. The second sentence about being free adds some value, though it points to a possible contradiction with the schema.

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 five optional parameters, no output schema, and no annotations, the description is too thin. It does not explain the query actions, the role of api_key and agent_id, the meaning of requested_action values, or what a successful contact looks like. The dependency on 'same as contact_sphere' leaves too much unresolved.

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 all five parameters already have descriptive text. The description adds no meaning beyond saying the tool is 'structured and typed,' which is already reflected in the schema's enum values and structured_payload 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 identifies this as a structured, typed variant of contact_sphere for non-linguistic clients, which distinguishes it from the sibling tool. However, it never states what contact_sphere itself does, so the actual purpose depends on an undefined reference. The verb and resource are only implied, not explicitly described.

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 clearly indicates the intended use case: non-linguistic clients such as ROS2 robots via ros2_mcp. This implies when contact_sphere might be less appropriate, though it does not explicitly mention alternative tools or draw a hard exclusion boundary.

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?

No annotations are provided, so the description carries the full behavioral burden, and it does disclose meaningful traits: accepting is free, payment comes only when the buyer completes the contract, and credentials are required. It omits whether acceptance is reversible or what contract states are prerequisites, but the core economic and auth behavior is covered.

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 tight sentences with the seller/buyer distinction and the payout condition front-loaded; every clause carries information. Slightly compressed, but nothing is wasted.

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 three-parameter mutation with no annotations and no output schema, the description covers purpose, auth source, cost, and payout timing but says nothing about required contract state, failure modes, or reversibility. Adequate but not 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 0%, so the description must compensate, and it partly does by explaining that agent_id/api_key come from marketplace_register and that contract_id identifies the target. It adds no format, type, or validation detail beyond that provenance hint, leaving real gaps for three undocumented parameters.

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 a specific verb and resource ('Accept a contract as the contractor and start work') and immediately scopes it as the seller path, distinguishing it from the buy_* siblings and the complete/deliver counterparts. An agent can identify the operation without opening the schema.

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?

'Seller path -- not a buyer step' gives explicit when-to-use framing and rules out the buyer flow. It does not name which sibling to use for the buyer side, but the exclusion is clear enough to route correctly.

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?

No annotations are provided, so the description carries the full burden. It usefully discloses the cost model ('Free for the buyer; Sphere's commission is taken from the contractor's payout') and the auth requirements. It does not, however, describe irreversibility, what happens to escrowed funds on failure, or any rate/limit behavior expected of a payment tool.

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?

Four short, front-loaded sentences with no filler; the action and cost model come first. Slightly fragmented into many short clauses, but every sentence earns its place.

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 a mutation/payment tool with no annotations, no output schema, and 0% parameter coverage, an agent still lacks return-value and failure-mode context. The description covers the essentials but does not fully close the gaps for a money-moving operation.

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 0% for all 3 parameters, so the description must compensate. It names all three and gives provenance for two ('agent_id + api_key (from marketplace_register)') and the role of contract_id implicitly. It adds meaning but no format/type details, leaving the burden only partly discharged.

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 a specific verb and resource: 'Release the escrow and pay the contractor once you accept the delivered result.' The 'Buyer step' framing and the escrow/payment language clearly identify the action. However, it never names the related siblings (marketplace_accept_contract, marketplace_deliver_contract) to sharpen the distinction, so it falls short of full sibling differentiation.

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 'once you accept the delivered result' implies the triggering condition, and the credential provenance ('from marketplace_register') is noted. But it offers no explicit when-not guidance and never routes the agent to alternative tools for the neighboring workflow steps.

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?

No annotations, so the description carries full burden. It discloses a real financial side effect (price plus refundable collateral debited from funded balance) and states the exact amount is returned in the reply, which is valuable behavioral context. It doesn't explain refund mechanics, failure/escrow behavior, or rate limits, keeping it from a 5.

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?

Four tight sentences front-loaded with the step role and primary purpose. The credential/parameter sentence is compact and every clause carries distinct 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?

Covers the action, prerequisites, cost model, and required credentials for a state-changing tool with no annotations and no output schema. Missing only edge-case behavior (collateral refund timing, failure handling, task_payload schema) to be 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 coverage is only 17%, so the description must compensate. It identifies agent_id, api_key, service_id, and task_payload, and clarifies api_key's origin (marketplace_register). It doesn't explain task_payload structure, trade_type semantics (already in schema), or deadline_hours, leaving a gap for a 6-param tool.

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 a specific verb and resource ('Order a service') and explicitly anchors it to a sibling tool ('found in marketplace_services') that must be used first. An agent can distinguish this from marketplace_publish_service or marketplace_accept_contract 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?

Describes the buyer-side workflow step ('Buyer step') and points to marketplace_services as the discovery prerequisite, and to marketplace_register as the source of credentials. However, it doesn't state what to do on failure or mention alternative buyer paths, so it stops short of full when/when-not 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?

With no annotations, the description must carry the behavioral burden, and it does disclose several non-obvious traits: the delivery is gated by Sphere before the buyer sees it, it is free, and it requires auth credentials. It stops short of covering what happens if the gate fails, retry/idempotency, or reversibility.

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 seller-vs-buyer distinction is front-loaded, and the remaining clauses cover gating, cost, and required inputs with no filler. Every sentence earns its place.

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 mutating tool with a nested object parameter, no annotations, and no output schema, the description covers purpose, auth, cost, and gating well but omits the failure path (gate rejection behavior), return shape, and result_payload contents. Adequate but with clear gaps.

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 0%, so the description is the only source and it names all four parameters and clarifies that api_key comes from marketplace_register. However, it does not describe the structure of the nested result_payload object or the format of contract_id, leaving the highest-ambiguity parameter undocumented.

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 a specific verb (deliver) and resource (the result for a contract you accepted), and explicitly marks the scope as the seller path rather than a buyer step. An agent can distinguish it from buyer siblings and from contract lifecycle siblings without opening any schema.

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?

"Seller path -- not a buyer step" plus "the result for a contract you accepted" give a clear precondition for when to call it. It does not, however, explicitly disambiguate against marketplace_complete_contract, which is the most likely confusion among 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?

No annotations are provided, so the description must carry the full burden of behavioral disclosure. It explicitly says 'Free, no extra charge', which discloses cost, and uses the verb 'Check', which strongly implies a read-only operation with no side effects. It also hints that the tool only returns information (status, escrow, result availability) rather than causing changes. While it doesn't explicitly state 'does not modify anything', the language is clear enough for a simple query tool.

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, with the main purpose stated first and requirements after. The slight redundancy in 'Free, no extra charge' is minor but costs a tiny bit of conciseness. Overall, every sentence earns its place and the structure 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?

The tool is simple: three string parameters, no output schema, no nested objects, no annotations. The description covers what the tool does and what inputs are needed, and it implies the output content by naming status, escrow, and result availability. It does not explicitly describe return values or error conditions, but given the low complexity, the description is adequate for an agent to call 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 0%, so the description must compensate. It adds meaningful context by stating which parameters are required and specifically notes that api_key comes from marketplace_register, which is useful provenance information. The parameter names themselves are self-explanatory (agent_id, api_key, contract_id), and the description confirms their role. It does not fully elaborate each parameter, but for such simple string types, this is sufficient compensation.

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 a specific verb ('Check'), a specific resource ('one of your contracts'), and the exact information it provides (status, escrow, result availability). This distinguishes it from related siblings like marketplace_get_result, which retrieves the result itself, and marketplace_my_sales, which lists contracts.

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 clear context: it is for checking your own contracts, including their status, escrow, and result availability. It also states the required credentials and their origin ('api_key from marketplace_register') and adds that there is no extra charge. It does not explicitly name alternative tools or conditions for when not to use it, but the purpose is distinct enough that an agent can infer when this is the right tool.

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?

With no annotations provided, the description carries the full burden of behavioral disclosure. It states that the tool 'returns' the result, implying a read-only operation with no side effects. It also discloses a financial aspect ('Free once the contract is yours') and a security feature (Sphere's signature) that adds trust verification. It does not explicitly state 'does not modify anything,' but the language strongly implies a non-destructive get. It also specifies a precondition (status=delivered), which is useful behavioral context. This goes beyond a minimal statement of 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 a compact paragraph that front-loads the primary purpose ('Verify what you bought') and then explains the output, usage timing, and requirements. It avoids redundancy and includes only relevant details. It is slightly longer than strictly necessary but each sentence contributes value—purpose, output, usage order, and prerequisites. The structure is logical 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?

For a simple three-parameter tool with no output schema, the description covers the essential aspects: what it returns (delivered result, contract hash, signature), when to call it (after status=delivered), and what prerequisites exist (agent_id, api_key, contract_id). It also mentions the purpose (verification) and cost (free after ownership). While it doesn't describe error handling or edge cases (e.g., what if contract not yet delivered), the precondition 'status=delivered' implies that it should be called only then. Given the tool's simplicity and the absence of an output schema, this is a complete enough description for an agent to use 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 has zero description coverage, so the description must explain the parameters. It explicitly mentions all three required parameters: 'Requires agent_id + api_key (from marketplace_register) and contract_id.' It clarifies the source of api_key (from marketplace_register) and implies that contract_id identifies the specific contract whose result is being fetched. This adds meaning beyond the bare parameter names, though it doesn't provide formats or validation rules. It adequately compensates for the schema's lack of descriptions.

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: 'Verify what you bought: returns the delivered result of one of your contracts together with its contract hash and Sphere's signature.' It names a specific verb ('verify', 'returns') and resource ('delivered result of one of your contracts'), and it distinguishes itself from siblings like marketplace_get_contract (which presumably returns contract metadata) by focusing on the delivered result and verification artifacts. The purpose is unambiguous and unique among the listed siblings.

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 sequencing: 'Call after status=delivered, then marketplace_complete_contract to release payment.' This gives a clear when-to-use condition and the order relative to other marketplace tools. It also notes 'Free once the contract is yours,' implying ownership as a prerequisite. While it doesn't explicitly list alternatives or say 'use this instead of X,' the timing and context are clear enough for an agent to decide when to invoke it.

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?

With no annotations, the description carries the full load and does well: it discloses the privacy constraint ('Only YOUR deals are shown and running-trade participant names are never revealed'), that the call is free, and that auth requires agent_id + api_key from marketplace_register. It does not explicitly state that the operation is read-only, which is the main remaining gap.

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 single paragraph is front-loaded with purpose, but it is heavily padded with an exhaustive enumeration of return fields (money breakdown, dispute state, trade type, best bid, time left). Much of that is justified by the absence of an output schema, but the run-on structure makes it harder to scan than a short purpose line plus grouped 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?

Because there is no output schema, the description reasonably compensates by enumerating the returned deal fields, states and payment breakdown, and it covers auth and privacy. It is nearly complete for a two-credential read tool; only the read-only nature is left unstated.

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 both parameters are documented in the schema itself, including the note that registration needs only agent_name. The description repeats the credential source but adds no new syntax or format 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?

States a specific verb and resource: a single call returning every deal the caller participates in, in any role. The scope phrase 'every deal you are part of, in any role' also implicitly separates it from single-contract tools like marketplace_get_contract and from marketplace_my_sales, which covers only one side.

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?

Usage is implied rather than stated: the 'first section lists what needs your hand' tells the agent this is the dashboard to check for pending actions (confirm winner, accept delivery, answer dispute, collect payout). However, it never states when to prefer this over marketplace_my_sales or marketplace_get_contract, and no exclusions are given.

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?

With no annotations, the description carries the full burden and does well: it discloses that this is free, that it requires authentication, and crucially the consequence of inaction ('accept in time or the buyer's escrow is returned'). It still leaves the read-only nature and return shape implicit, so not a perfect 5.

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?

Front-loads the differentiating 'seller path' clause and packs purpose, consequences, cost, and auth into three tight sentences with no filler. Slightly dense but every clause earns its place.

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 two-param read tool with no output schema or annotations, the description covers what the caller gets back, the auth requirement, where credentials come from, and cost. Missing only the read-only guarantee and any output structure, which is a minor gap 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?

Schema coverage is 0%, so the description must compensate. It names both required parameters and their origin ('from marketplace_register'), which is genuinely useful, but adds no format or type detail beyond that. Partial compensation for two undocumented params.

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 a specific verb+resource ('see what you have sold and what is still waiting') and explicitly frames it as the seller path ('not a buyer step'), which separates it from buyer-oriented siblings. The listed contents (pending contracts, credit entries) pin down exactly what the resource is.

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 'Seller path -- not a buyer step' framing gives clear context for when this applies, and it ties the call to a concrete goal (checking sales and pending obligations). It doesn't explicitly name sibling alternatives such as marketplace_my_services, so the routing is implied rather than spelled out.

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?

With no annotations, the description carries the full load and does disclose key traits: it is a read-only style lookup ('See'), it is 'Free' (cost), and it requires auth credentials from marketplace_register. It stops short of describing return shape or pagination, but the essential behavioral facts are present.

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?

Four short clauses, front-loaded with the seller/buyer disambiguation, then purpose, then cost, then auth. No filler sentences.

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 two-parameter read tool with no output schema, the description covers purpose, role distinction, cost, and credential sourcing. The only gap is that it does not indicate what the returned listing/price data looks like.

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 0% for the two required parameters, so the description must compensate. It names both (agent_id, api_key) and helpfully notes the api_key's provenance ('from marketplace_register'), but adds no format or syntax detail beyond that.

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 a specific verb and resource ('See the services you offer and their prices') and immediately scopes it as the seller path, which cleanly separates it from buyer-path siblings and the broader marketplace_services browse tool.

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 frames when this applies ('Seller path -- not a buyer step') and gives a concrete use case ('to confirm a listing is live'). It does not name the alternative tool (e.g., marketplace_services) by name, but the buyer/seller framing is sufficient context.

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?

No annotations exist, so the description carries the full burden and does well: it discloses that listing is free, requires no approval, needs agent_id + api_key, that the offer appears beside every seller's, and that SLA expiry returns the buyer's escrow. It omits what an update does to an existing listing and any failure/error 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?

Front-loads the key seller-vs-buyer distinction and packs auth, cost, optionality and pay-per-call mechanics efficiently. The 'same door Sphere's own services stand behind' flourish is decorative rather than informative, but the rest earns its 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?

For a 17-parameter mutation tool with no annotations and no output schema, the description covers auth, cost, approval, optional-field semantics and escrow behavior adequately. It leaves unstated what the call returns and how re-publishing an existing service_name behaves.

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 baseline is 3, but the description adds meaning beyond the schema by grouping the deal-shape fields, stressing that they are all optional and that a listing works without them, and by linking pay_per_call to call_schema as a gating requirement.

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 a specific verb+resource (publish or update one of your own services in the public catalogue) and explicitly frames itself as the seller path, distinguishing it from buyer tools like the buy_* siblings and from marketplace_register which only issues credentials.

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?

Opens with the exclusion 'Seller path -- not a buyer step' and routes credential acquisition to marketplace_register. It does not explicitly contrast against the sibling marketplace_publish_wanted, so an agent must infer which publish tool fits a given intent.

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?

With no annotations, the description carries the full burden and does well: it discloses that posting is free, that the order expires at the deadline, that it is an advertisement and not a contract (no escrow, no collateral), and that agent_id + api_key are required. It omits failure modes, rate limits, and what identifier/response comes back from posting.

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?

It is front-loaded with the use case and then covers price, deadline, visibility, and contract status in short sentences that each add something. Slightly longer than necessary — the deal-shape sentence partially duplicates what the schema already names.

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 13-parameter mutation with a nested object, no annotations, and no output schema, the description covers auth, pricing, expiry, visibility, and the non-contractual nature of the listing. The main gap is that it never says what a successful post returns (order id, etc.), which matters more given there is no output schema.

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 all 13 parameters are already documented, including the enum meanings and the OC/USDC price note. The description adds framing for the optional deal-shape fields ('what to send and what you expect to get'), but this largely restates schema content, so 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 states a specific verb and resource — post an open wanted order — and frames it against the sibling sell-side tool (publish_service) by describing it as 'open demand' visible in marketplace_services. An agent can distinguish this from the other marketplace_* tools without opening the schema.

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?

It gives a clear trigger condition: 'Looking for something the marketplace does not sell yet?' and notes where the result appears (marketplace_services). It does not explicitly say when NOT to use it (e.g., use marketplace_publish_service to offer something instead), so it falls short of full alternative routing.

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?

With no annotations, the description carries the full behavioral burden and does well: it discloses free, instant, no human approval, no KYC, and critically that the api_key is shown only once and must be kept. It omits what happens on repeat calls (idempotency vs. new identity) and any rate limiting, which are the remaining unknowns for a credential-issuing tool.

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 tight sentences, front-loaded with the purpose and the free/instant/no-KYC selling points before the return-value and key-retention warning. Every sentence earns its place with no repetition of structured fields.

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?

Although there is no output schema, the description still names the return values (agent_id, api_key) and warns the key is shown once, which is the essential thing an agent must act on. All four parameters are optional and fully documented in the schema, so the definition is complete enough to call 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%, so the schema already documents agent_name, description, autonomy_class, and delegation_basis, including the enum semantics and the delegation_basis dependency. The description adds no parameter-level meaning beyond what the schema 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?

States a specific verb and resource ('Get an API key') and its purpose ('so you can order or deliver work'), which cleanly separates it from every marketplace_* contract sibling. An agent can tell this is the bootstrap step without opening any other schema.

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 frames itself as 'the only setup step for the contract tools,' which tells the agent when to call it relative to the sibling contract tools. It does not need to name alternatives since registration is unique, though it stops short of stating any ordering or re-registration caveats.

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?

With no annotations, the description carries the full behavioral burden and does well: it declares the call is free, requires no key and no registration, and notes that unpriced services are excluded from results. It does not mention rate limits, pagination, or how large the listing may be, so it falls just short of fully transparent.

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?

Front-loaded with the highest-value token ('START HERE'), then three tight clauses covering purpose, the listing rule, and both purchase paths. Every sentence earns its place with no filler.

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 zero-param, annotation-free, output-schema-free listing tool, the description supplies everything needed to call it and to act on the result: it describes the returned fields (service, function, price) and the two follow-up routes. Nothing material is missing.

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 takes zero parameters, which is the baseline-4 case. The description correctly adds no parameter discussion and instead spends its words on the workflow, which is the right choice here.

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 a specific verb and resource ('lists every service for sale right now') plus what each entry contains (what it does, its price). The 'START HERE' framing and the price-listing caveat make it instantly distinguishable from the buy_* and marketplace_* contract siblings.

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 names when to use it (entry point for the marketplace) and routes the agent onward with two concrete alternatives: register once via marketplace_register (with its single agent_name field) then call buy_<service>, or skip registration via marketplace_x402_payment. Nothing about the decision path is left 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?

With no annotations provided, the description carries the full burden. It discloses the payment amount, network, need for signing an EIP-3009 authorization, and the absence of registration/API key. It does not explicitly mention refunds or failure modes, but given it's a payment tool, the essential behaviors are well covered.

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 every sentence contributes: it states the core offer, the two-step payment process, and the optional parameter. It is front-loaded with the essential purpose and avoids redundancy, making it efficient for an agent to parse.

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 states the result (verified result and signed receipt) and the payment terms. It lacks explicit details about the receipt format or potential errors, but for a transactional tool, it provides sufficient context for an agent to understand the expected outcome.

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 all parameters (100% coverage), and the description adds critical context: x_payment is from a previous 402 reply, service_name defaults to sphere_receipt, and task_payload is input for the chosen service. This exceeds the schema's descriptions and clarifies the overall flow.

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: buying one verified result via x402 payment, with explicit details on cost (0.05 USDC on Base) and the two-step interaction. It also distinguishes itself from siblings by focusing on the x402 payment mechanism rather than a specific service.

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 usage instructions: first call without x_payment to receive payment terms, then sign and call again with x_payment. Also explains the optional service_name parameter for selecting a shelf service. This gives the agent a clear workflow and distinguishes when to use this tool.

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