EpicPxls

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

Goes well beyond the annotations by disclosing side effects (email with download link and receipt is sent to the buyer), a concrete TTL (link expires after 24 hours), and the human-in-the-loop handoff (payment completed on Stripe's hosted page). This is exactly the operational context the schema and hints cannot convey.

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 core action, then the email requirement, then the free-item branch and expiration. No filler or redundant restatement.

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 present, the description correctly supplies the return behavior (checkout link for paid items vs. free download URL) and the key constraints. An agent has everything needed 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 description coverage is 100%, so both parameters are already documented. The description restates the email's purpose (receipt/download delivered there) and only loosely associates slug with 'EpicPxls item', adding no syntax or format detail beyond the schema. Baseline 3 for fully covered 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 (Create) plus resource (Stripe checkout payment link) and scopes it to paid EpicPxls items, with an explicit branch for free items. An agent can immediately tell this is the only write/payment-initiation tool among read-oriented siblings like get_item and get_free_assets.

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 clear conditional context: use for paid items, and for free items the tool returns the free download URL instead. It does not name the sibling tool (e.g. get_free_assets) that an agent should prefer for free assets, so the routing is implied rather than explicit.

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, openWorldHint, and destructiveHint=false, so the safety profile is covered. The format constraint the description adds (PNG only) is largely duplicated by the schema's 'HTTPS URL of a PNG image' description, so it contributes little new behavioral context beyond noting the fallback path.

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, no filler, with the core capability front-loaded and the format restriction/fallback placed after it. 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?

There is no output schema, and the description does state the return form (hex codes), which covers the main return-value question. Minor gaps remain, such as ordering/sorting of colors or error behavior on an oversized or unreachable image, but the tool is simple enough that this is close to 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 100%: count documents its range and default, and image_url documents format and size limit. The description adds no parameter-level detail beyond that, 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 (extract), resource (dominant color palette), input type (PNG image URL), and output format (hex codes). No sibling in the list (checkout links, fonts, assets, items) overlaps with palette extraction, so there is no confusion to resolve.

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 an explicit when-not condition plus an alternative: 'For JPEG/other formats use the web tool at ...'. An agent knows exactly which input this tool accepts and where to route unsupported inputs.

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 readOnly, idempotent, and non-destructive, so the safety profile is covered. The description adds genuinely new context beyond that: returned fields (prices, free/paid status, style tags), the preview_url that renders the user's own text, and the licensing fact that all fonts carry a commercial license.

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 with the purpose front-loaded and return details trailing, which is the right ordering. It loses a little by restating the schema's query examples verbatim rather than using the space for new 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?

With no output schema, the description correctly shoulders the burden of explaining return values (prices, free/paid flag, style tags, preview_url) and license terms. It does not mention result limits, pagination, or what an empty result looks like, a minor gap for a catalog search.

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 the description's query examples ('script', 'serif', 'display', 'handwritten', 'wedding invitation', 'logo') simply repeat the schema's own examples. It adds no syntax, format, or default 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 gives a specific verb+resource (find fonts in the EpicPxls catalog) and scopes it by the three query axes: name, style, and use. It is clearly a font-domain search, but it never distinguishes itself from the generic sibling search_items, so an agent must infer the boundary.

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 implies usage by listing valid query types and mentioning free_only indirectly, but offers no explicit when-to-use or when-not-to-use guidance and names no alternative tool. With search_items and get_item among its siblings, an agent gets no routing help.

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 a read-only, idempotent, non-destructive, closed-world operation, so the safety profile is covered. The description still adds real value beyond them by disclosing the auth requirement ("No account required") and the nature of the payload ("direct download-page URLs"), which the agent cannot learn from annotations or the absent output schema.

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?

A single sentence that front-loads the verb and resource, with the qualifiers (FREE, most-downloaded, download-page URLs, no account) immediately after. Nothing redundant, and the parenthetical type list helps query matching without padding the 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?

For a two-optional-parameter read tool with no output schema, the description covers what is returned (download-page URLs) and the auth posture, which is the key missing context. Minor gaps remain around pagination/ordering of the "most-downloaded" list and how `category` values should be formatted, but nothing blocking correct 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 description coverage is 100%, with both `limit` (default 10, max 25) and `category` fully documented in the schema itself. The description's parenthetical asset-type list loosely hints at category values ("Fonts", "UI Kits") but adds no syntax, default, or filtering behavior beyond what the schema provides, 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 ("Get") and resource ("EpicPxls' most-downloaded FREE design assets") with concrete asset types, scoping it to a curated top-downloads list rather than a general search. It never names or contrasts with siblings such as search_items or list_free_tools, so the boundary is inferred rather than stated.

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 only implied: the "most-downloaded FREE" framing suggests this is for browsing a curated free-asset list rather than searching or fetching a single item. There is no explicit when-to-use, no when-not-to-use, and no reference to the alternatives (search_items, list_free_tools, get_item) that an agent must choose between.

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 readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely useful context the annotations do not: it enumerates the payload (price, license, preview images, download/buy URL), which matters because there is no output schema.

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?

One sentence, front-loaded with the verb and resource, with the returned-field list appended as useful detail. 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?

With no output schema, the description carries the burden of describing the return value and does so adequately by naming the key fields. It omits error behavior (e.g. unknown slug) and any note on whether the buy/download URL is time-limited, which keeps it short of a 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?

There is a single parameter at 100% schema description coverage, so the schema already documents it. The description's "by slug" restates the schema and adds no format, lookup, or identifier guidance beyond it — baseline 3.

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 gives a specific verb ("Get full details") and a bounded resource ("one EpicPxls item by slug"), which clearly separates it from list/search siblings. It stops short of naming the sibling it contrasts with (e.g. search_items, get_item_screens), but the scope is 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 phrase "one EpicPxls item by slug" implies the precondition (you already have a slug) and the natural alternative (search_items for discovery), but neither is stated explicitly. No when-not guidance or prerequisite is 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?

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered. The description adds useful context about what the images are (source-file renders, not product screenshots), but says nothing about return format (URLs vs base64), pagination behavior, or failure modes for a bad slug. This is modest added value over structured fields, fitting a 3.

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 short sentences, each earning its place: purpose, artifact nature, and use case, in that order. The core verb and resource are front-loaded with no preamble or 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?

There is no output schema, so the description must carry return-value context, yet it never explains how the images come back (URLs, base64, metadata) or how the limit interacts with results. For a simple 2-parameter getter the gap is not fatal, but it leaves a meaningful unknown for an image-retrieval 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 both slug and limit are already documented in the schema, including the default of 3. The description adds no parameter-level detail such as slug format or pagination semantics. Baseline 3 is correct when the schema carries the full parameter burden.

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 gives a specific verb and resource: retrieving screen images rendered from an EpicPxls item source file (Figma or PSD). It further clarifies the artifact type (full app screen at native resolution, not a shipped-product screenshot), which conceptually separates it from get_item and get_free_assets. However, it does not name or contrast against any sibling tool, so it falls just 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 states an explicit use case: "Use these as visual reference when designing an interface." That gives a clear context for invoking the tool. It stops short of exclusions or naming alternatives (e.g., extract_palette or find_fonts for non-visual needs), so a 4 is appropriate 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?

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed world, so the safety profile is covered. The description adds value on top by disclosing the return content (item counts and browse URLs), which matters since no output schema exists; it stops short of noting ordering or pagination.

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?

A single front-loaded sentence with no filler; every clause earns its place by naming the resource and the three things returned.

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 no-argument, read-only list tool with no output schema, the description needs to characterize the response and does so (categories with counts and URLs). Given annotations carry the safety profile, this is nearly complete; only ordering/pagination behavior is unstated, which is minor for a closed, finite category list.

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?

There are zero parameters, so per the baseline this dimension scores 4. Nothing in the description is needed to clarify inputs, and it correctly does not invent any.

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 (list categories) plus what each entry contains (item counts, browse URLs), so the agent knows exactly what it gets back. It does not explicitly contrast itself with siblings like search_items or get_item, but the resource is unmistakably distinct.

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

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

No when-to-use guidance is offered — nothing tells the agent to call this before search_items, or as a discovery step, or as an alternative to list_free_tools. The purpose is implied but no conditions or exclusions are 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?

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds no behavioral context beyond that — nothing about whether the list is static or fetched live, or what form the entries take. Consistent with annotations, but no added value.

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?

Single front-loaded sentence with the resource named first; structurally sound. The ten-item parenthetical is long but earns its place by previewing the catalog contents an agent may need to match user intent against.

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, read-only listing tool with complete annotations and no output schema, the description covers what it needs. It only falls short on return shape (names/URLs/counts), which an agent could reasonably want when deciding whether this call answers a user's request.

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, so there is no parameter semantics to explain and the baseline is 4. Nothing in the description is needed to compensate for schema gaps.

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?

It states a specific verb and resource ("List EpicPxls' free browser-based design tools") and enumerates exactly what counts as a tool, so an agent knows the payload scope. It does not, however, differentiate itself from overlapping siblings such as get_free_assets (free assets) or find_fonts, which is literally one of the enumerated items.

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 only implied by the resource name: an agent can infer this is the discovery call for available design utilities. There is no explicit when-to-use statement, no when-not-to-use, and no alternative (e.g. get_free_assets) named for the adjacent discovery case.

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 readOnly, idempotent, and non-destructive, so the safety profile is covered. The description adds genuinely useful context beyond that: catalog scale, the licensing model (commercial license on all items), and that most items ship editable Figma/Sketch/PSD source. It omits pagination behavior and result-count limits.

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, all load-bearing: the first defines scope, the second tells the agent what comes back, the third covers licensing and source-file availability. Front-loaded with the catalog identity and zero 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?

With no output schema, the description correctly picks up the burden of describing returns (prices, free/paid status, page URLs) and licensing. It is nearly complete; it does not explain the 'page' parameter's practical limits or how result sets are sized, which is the only real gap for a paginated search 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 all four parameters are already documented, including the with_screens flag's intended follow-up with get_item_screens. The description adds no parameter-level meaning of its own, 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 ('Search EpicPxls' catalog of 65,000+ design resources') and enumerates the resource types covered. It is clear what the tool does, but it does not distinguish itself from search-like siblings such as find_fonts or get_free_assets, which an agent must disambiguate on its own.

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

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

No when-to-use, when-not-to-use, or alternative routing is provided. The description never mentions find_fonts, list_categories, or get_free_assets, leaving the agent to infer that this is the general query entry point while those siblings handle narrower cases.

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