Fabric Marketplace

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

Annotations are all false and provide minimal behavioral hints. The description compensates by disclosing that the tool creates a new identity, requires no authentication, returns specific items, and mandates post-creation steps (persist node.id/api_key, configure recovery_public_key, configure webhook/polling). It also warns against using it when an existing node exists, implying non-idempotency.

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 about five sentences long, with each sentence carrying distinct, non-redundant information: purpose, non-credential-refresh clarification, usage alternatives, auth requirement, return values, and post-creation actions. It is front-loaded with the core 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 that there is no output schema, the description appropriately enumerates return values (node profile, API key, credit grant, setup guidance) and includes both prerequisites and follow-up steps. This makes it complete for a creation tool without requiring external knowledge.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema already provides 100% description coverage for all five parameters, including detailed semantics for recovery_public_key. The description adds only minor extra context (e.g., 'configure recovery_public_key') but does not need to compensate since schema coverage is high. 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 opens with 'Create a new Fabric participant identity (node) and receive an API key + 500 free credits,' which clearly identifies the verb, resource, and outcome. It also differentiates from siblings by explicitly stating it is not a credential refresh tool and referencing login_session/recovery as alternatives.

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 when-to-use and when-not-to-use guidance: 'Do not use this if the participant already has a node' and directs to alternatives (fabric_login_session when headers are unavailable, recovery if the API key is lost). It also notes that no authentication is required, which is a key prerequisite.

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

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

Annotations already declare this as readOnly, idempotent, and not destructive. The description adds value beyond those by disclosing 'No authentication required,' which is a behavioral trait not present in the annotations. It also describes the data fields returned. There is no contradiction or missing critical behavioral context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences with no filler. The first sentence front-loads the core function and expected output, the second gives actionable usage guidance and an access note. Every sentence earns its place, and the text is appropriately sized for the tool's simplicity.

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?

Without an output schema, the description compensates by explicitly listing the data fields (IDs, slugs, names, descriptions, examples). It covers access requirements (no auth) and how to apply the result (use IDs when creating units/requests). For a parameterless read-only getter, this is complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has 0 parameters, and the schema is an empty object, so schema coverage is effectively 100%. Per the guidelines, 0 parameters gives a baseline of 4. The description adds no parameter-level detail because there are none, but it does explain the purpose of the returned data, which is sufficient for this 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?

The description starts with 'Get the full category registry', a specific verb+resource combination that clearly states what the tool does. It also enumerates the contents (IDs, slugs, names, descriptions, examples), which further clarifies the purpose and distinguishes it from siblings like fabric_get_meta or fabric_get_regions.

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 clear usage context: 'Use category IDs when creating units/requests.' This tells the agent when to use the tool's output. It also notes 'No authentication required,' which sets expectations. However, it does not explicitly name alternative tools or state when not to use this tool, so it stops short of full exclusionary 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?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds behavioral value by stating 'No authentication required,' which is not captured in annotations. It also implies the returned metadata is needed before bootstrap, giving context beyond safety hints.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loaded with the action ('Get Fabric service metadata') and followed by essential context (no auth, before bootstrap). Every sentence earns its place with no redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

This is a simple metadata fetch with no parameters and no output schema. The description covers purpose, the type of data returned, authentication requirements, and when to call it, making it complete for an agent to select and 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?

The tool has zero parameters, so the baseline is 4. The description doesn't need to explain parameters since there are none. No additional parameter info is necessary.

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 gets Fabric service metadata, listing specific content (legal version, API version, URLs). It distinguishes itself from sibling tools like fabric_get_categories and fabric_get_regions by covering general service metadata rather than a specific subset.

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 explicit usage guidance: 'Call this before bootstrap to discover the service.' This communicates when to use it. It doesn't explicitly mention alternatives or when not to use it, but the context is clear enough for a simple metadata retrieval 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?

Annotations already indicate read-only, idempotent, and non-destructive behavior. The description adds valuable extra context: 'No authentication required' discloses an important access requirement, and 'Returns ISO 3166-1/2 codes' clarifies the output format, which is crucial since no output schema exists. This goes beyond what annotations provide.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is extremely concise—two short sentences that front-load the purpose and immediately provide key behavioral details (no auth, output format). Every word earns its place, with no redundant or irrelevant information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with zero parameters, no output schema, and simple functionality, the description is complete. It states the purpose, specifies the output type (ISO codes with examples), and notes authentication requirements. Nothing essential is missing for an agent to use 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?

This tool has zero parameters, so the baseline is 4. The description does not need to explain parameter meanings. The empty input schema covers parameter details, and the description adds no parameter-specific information because none exists.

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: 'Get supported region codes for search filters and scope fields.' It uses a specific verb and resource, and the mention of 'region codes' distinguishes it from siblings like fabric_get_categories (categories) and fabric_get_meta (meta).

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 clear usage context by stating the codes are for 'search filters and scope fields,' implying when the tool is relevant. It does not explicitly mention alternatives or when not to use it, but the sibling tools cover different domains, so the context is sufficient.

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

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

Annotations are all false, providing no behavioral hints. The description adds that the token is short-lived and that no authentication is required, which goes beyond the schema. However, it does not disclose details like token lifespan, side effects, or error conditions, leaving a transparency 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?

Two concise sentences, front-loaded with the action. 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, the description covers purpose, usage context, and a constraint. It lacks mention of token usage or specific expiry, but the 'short-lived' qualifier and the provided context suffice. Given low complexity, it is relatively 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% and already describes the api_key parameter. The tool description does not add additional meaning beyond the schema, so with high schema coverage, a baseline score of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool creates a short-lived MCP session token from an API key, with a specific verb and resource. It distinguishes itself from sibling tools like fabric_create_identity and fabric_get_categories by focusing on session token creation.

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 says 'Use this when your MCP runtime cannot reliably set Authorization headers', providing a clear condition for use. However, it does not mention when not to use it or alternative tools, so it lacks explicit exclusions.

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

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

Annotations only set all hints to false, providing little safety profile. The description supplements this by disclosing the return value (new API key), the two input options (signature/code), and the lack of authentication. It does not go into side effects or failure modes, but annotations are not contradicted, and the added context covers the essential behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences convey the core action, both input modes, output, and an important condition (no authentication). No filler or repetition; every sentence is essential and 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?

With no output schema, the description correctly states the return value. It explains both recovery paths and the challenge_id prerequisite. The tool is simple enough (3 parameters, no enums) that all essential usage context is covered in the description.

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 descriptions cover all parameters (100%), and the description adds the key semantic that 'signature' and 'code' are mutually exclusive alternatives. This clarifies the relationship between the three parameters beyond the schema alone.

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 uses a specific verb and resource ('Complete account recovery') and clearly states the outcome ('Returns a new API key'). It distinguishes from the sibling fabric_recovery_start by implying this is the follow-up step, but it does not explicitly name the former.

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 after fabric_recovery_start by referencing 'challenge_id' and the two alternative recovery modes. It also adds a key condition: 'No authentication required.' It does not explicitly contrast with alternatives, keeping it a point short of 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?

With all annotations being false, the description compensates by stating 'No authentication required' and describing the expected outputs (a nonce for pubkey, a 6-digit recovery code for email). This adds behavioral context beyond the annotations, though it does not fully articulate server-side side effects or error 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 description is two sentences, front-loaded with the primary purpose, then immediately providing actionable method-specific guidance. Every sentence contributes value with no redundancy, achieving excellent conciseness.

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?

Despite lacking an output schema, the description explicitly tells the caller what they will receive for each method (nonce or recovery code) and the prerequisites (verified email, node ID). This is sufficient for an agent to invoke the tool correctly, especially given the sibling fabric_recovery_complete for the next step.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema covers all parameters with descriptions (100% coverage), so the baseline is 3. The description reinforces the relationships between method and the other parameters but does not add substantially new semantic information beyond what the schema already provides.

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 precisely states 'Start account recovery if you lost your API key', using a specific verb and resource. It also outlines two distinct methods (pubkey and email) with their respective parameters, making it clearly distinguishable from the sibling tool fabric_recovery_complete which handles the next step.

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 clear use cases (when you lost your API key) and detailed instructions for each method, including requirements like node_id for pubkey and a verified email for email. It does not explicitly mention when not to use this tool or alternatives, but the context is clear enough to guide correct selection.

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