Defici Marketplace MCP Server

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 that contact details are excluded, that all listing statuses (active/sold/expired) return results, and preemptively explains the currency_note field. This is notable behavioral disclosure for a read-only fetch tool. Could have mentioned return format, but this is a fetch-by-id utility where behavior is fairly obvious.

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

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

The description is compact — three sentences covering purpose, status scope, and the currency_note caveat. It's front-loaded with the verb+resource and each sentence earns its place. Slightly longer than necessary but every statement adds value, particularly the currency_note disclosure which prevents agent confusion.

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 single-parameter fetch tool with 100% schema coverage, the description is quite complete. It covers result conditions, an important exclusion (contact details), and preemptively explains a surprising field (currency_note). No output schema exists, so describing the currency_note field compensates partially for that gap. The description is adequate for agent selection and invocation.

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% (the single 'id' parameter is described as 'Listing UUID (e.g. from search_listings results)'). The description reinforces this by stating UUID usage but doesn't add much beyond the schema. Baseline 3 applies since the schema handles the parameter documentation well.

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

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

The description clearly states the verb ('Fetch'), the resource ('full details for a single listing'), and identifies it by 'UUID'. It distinguishes from siblings: search_listings is for searching, while this is a single-listing detail fetch. The marketing of scope (active/sold/expired) adds clarity.

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 specifies when to use it (fetching full details for a single listing by UUID), and implicitly distinguishes from search_listings (which returns lists/results). It clearly states contact details are NOT returned, directing users to the web interface instead — an explicit negative scope statement. No explicit naming of alternatives, but sibling differentiation is implied via the UUID-single-listing nature.

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. While it doesn't mention safety (this is presumably a read-only fetch tool), it does disclose the output fields (id, country, currency, languages), which gives the agent expectations about what the response will contain. Given the low risk nature (a list of static regions) and 0 parameters, the disclosure is reasonably complete, though it could note that no input is required.

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, zero wasted words. The first sentence states the purpose and output fields; the second provides the actionable usage tip connecting to search_listings. This is textbook conciseness with front-loaded purpose.

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-parameter, no-output-schema tool that returns static market data, the description is fully adequate. It states what is returned, the fields included, and how to use the result. There are no nesting complexities, required parameters, or side-effects to disclose. The tool is simple enough that this description is genuinely 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 zero parameters, so the baseline is 4 per the rubric. The description appropriately references the returned 'region id' as a consumable value, which indirectly gives the agent context about the meaningful output. With no parameters, there's little parameter semantics to add.

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 precisely what the tool does: 'Return all supported market regions' with their specific fields (id, country, currency, languages). It clearly distinguishes itself from siblings (get_listing, list_categories, search_listings) by being the market-lookup tool. The verb 'Return' plus resource 'market regions' is specific and unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly tells when to use it and how: 'Use the region id as the market argument in search_listings.' This is an explicit cross-reference to a sibling tool, providing clear guidance on the tool's role in a workflow. This is exemplary usage guidance since it connects this tool's output to consumption by another 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 burden. It discloses the tool returns a taxonomy and that the ids are used in search_listings. It doesn't describe return format, ordering, or whether this varies by region, but with zero parameters and a simple read operation, the behavioral disclosure is reasonably adequate relative to complexity.

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, zero waste. Every word earns its place: states the resource, names the platform, and connects the output to a downstream tool. Perfectly front-loaded with the core purpose.

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 parameterless tool with no output schema, the description is appropriately complete. It explains what's returned (category taxonomy), and why the agent should call it (to feed category ids into search_listings). A richer description would describe the shape of the taxonomy, but given the tool's simplicity, this is adequate.

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, so the baseline is 4. There are no parameter semantics to elaborate, and the description appropriately focuses on the output/usage rather than parameters. Nothing more is needed 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?

The description clearly states the tool returns the complete category taxonomy for Defici.com, with a specific resource ('category taxonomy'). It also distinguishes the purpose by explaining the relationship to search_listings via the category id values. This is a specific verb-resource pairing with clear scope.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly tells the agent when to use this tool: to obtain category id values that serve as the category argument in search_listings. It provides clear usage context by connecting to a sibling tool. It doesn't explicitly state exclusions/when-not-to-use, but the connection to search_listings effectively establishes the workflow 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 are provided, so the description carries full burden. It excellently discloses the critical caveat that prices are raw numbers with no confirmed currency unit, explicitly warns against treating price as a specific denomination or comparing values, and even explains the currency_note field structure in results. This is valuable behavioral context beyond what the schema provides.

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 front-loaded with purpose and reasonably compact. It packs significant value into a few sentences, with the critical currency caveat getting prominent placement. Slightly redundant with the price_max/price_min parameter descriptions that repeat the currency warning, but overall 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?

Given no annotations and no output schema, the description carries substantial burden and handles it well. For an 8-param discovery tool with pagination and cross-market nuance, it covers the critical behavioral caveats (currency ambiguity), return structure (paginated, currency_note field), and safety profile (read-only). The mix of data-quality disclosure plus result-shape guidance is strong for a complex tool.

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

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

Schema description coverage is 100%, so the baseline is 3. The description adds contextual meaning for price parameters (warning currency issues) and references get_regions and list_categories for market/category valid values, which complements the schema. However, most parameter semantics are already well-covered by the input schema descriptions themselves.

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 'Search active listings on Defici.com global marketplace' with a specific verb and resource, and distinguishes itself from siblings by noting it returns paginated results and does not include contact details. It's distinct from get_listing (single-item fetch), get_regions, and list_categories.

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 brands this as a read-only discovery tool and notes that contact details are not included, which helps agents know when NOT to use it (e.g., for contacting sellers). However, it doesn't explicitly name sibling alternatives like get_listing for a single result, or explicitly state when to choose it over other tools.

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