ISBN digit shape

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does usefully state that page content is not stored, which is relevant for a URL-checking tool. However, it remains silent on key behaviors: what happens with invalid URLs, whether the URL is normalized, why `json` and `zone` are accepted, and what the exact response format is.

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 short sentences with zero filler. The core behavior is front-loaded, and the non-storage disclosure earns its place as a meaningful caveat. Nothing could be trimmed without losing 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 4 optional parameters, no output schema, and no annotations, the description is too thin. It explains only the URL-related behavior and leaves the role of the other three parameters unexplained. An agent cannot confidently predict the return value or know how `json` and `zone` affect the call.

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 has 100% coverage with descriptions for all four parameters, so the baseline is 3. The description adds no meaning beyond the schema — it only mentions URL, while `host`, `json`, and `zone` are left entirely to their schema 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 states a clear verb and resource: 'Return host, scheme, and HTTP status for a URL.' It is unambiguous about what the tool produces. However, it does not differentiate from sibling tools or explain why the tool also accepts `json` and `zone` parameters, leaving some ambiguity about the full 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?

No guidance is given about when to use this tool versus alternatives or when not to use it. The description only states what it returns; there are no conditions, exclusions, or references to sibling tools.

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 behavioral disclosure. It does add one meaningful trait: 'No identifiers are retained,' which alerts the agent to a data-retention guarantee. However, it fails to disclose whether this is a read-only classification, whether inputs are executed, or what side effects occur, so the behavioral picture remains incomplete.

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

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

Two short sentences with no filler. The primary action is stated first and the privacy note is a meaningful addition. Every word 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?

The tool has four parameters, no output schema, and no annotations, yet the description only states a vague classification purpose plus a privacy guarantee. It does not clarify what the classification result looks like, how parameters relate to the operation, or what an agent should do with the output. This leaves a significant gap for 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%, so the schema already documents all four parameters. The description adds no parameter-level meaning beyond the schema, such as which inputs are expected together or how they influence the classification. 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 a verb and a resource ('Show how this request is classified'), but it is vague about what 'classified' means and how it relates to the tool name 'compatibility'. It does not clearly differentiate from siblings like 'citation' or 'validate', leaving the agent to guess the intended 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 provides no guidance on when to use this tool versus alternatives. It neither names explicit conditions nor mentions exclusions. The only context given, 'No identifiers are retained,' is a privacy note, not a usage guideline.

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 behavioral disclosure, but it only mentions what the tool does not provide (WHOIS/ownership data). It does not state whether the operation is read-only, what is returned, how url/json/zone are processed, or whether anything is mutated. The limitation disclosed is useful but far from sufficient.

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 one short sentence with no filler, and the key differentiator ('without WHOIS or ownership data') is included. It is concise and front-loaded, though its brevity comes at the cost of important context that is penalized under completeness.

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 4 parameters, no annotations, and no output schema, the description is incomplete. It only addresses hostname splitting, leaving url, json, and zone entirely unexplained, and gives no sense of return values. The missing output schema and annotations place the full burden on the description, which it fails to meet.

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 no parameter-level meaning beyond loosely mapping to 'host'; it does not clarify how url, json, or zone relate to the operation. The schema already documents each parameter, so the description neither helps nor hurts 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 names a specific verb and resource ('Split a hostname into labels') and a distinguishing exclusion ('without WHOIS or ownership data'). However, the parameter set (url, json, zone) suggests the tool does far more than split hostnames, so the stated purpose is incomplete and partially mismatched with the actual 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?

No guidance is given on when to use this tool, what inputs are appropriate, or how it relates to alternatives. The only usage hint is the exclusion of WHOIS/ownership data, which is a data limitation rather than a usage condition. An agent cannot infer when to call it versus a sibling 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. 'Common IANA timezone names for clock calls' weakly implies a read-only reference resource, but it does not disclose what happens when invoked, whether inputs are validated, what is returned, or whether any side effects occur.

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 short and has no filler words, which is structurally concise. However, it is under-specified to the point that the structure is more a fragment than a useful tool explanation; clarity was sacrificed for brevity.

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 four optional parameters that include url, host, and json, the description does not adequately explain how the tool should be called or what an agent should expect. With no output schema and no annotations, an agent cannot confidently determine inputs, outputs, or behavior.

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 four parameters. The description adds only a slight connection between 'IANA timezone names' and the 'zone' parameter, but does not clarify why url, host, and json are present or how they relate to the tool's purpose.

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 the resource ('common IANA timezone names') and a usage context ('for clock calls'), but it lacks a verb and does not state what the tool actually does — returns a list, validates a zone, or something else. It does not differentiate from sibling tools such as 'timezone' or 'validate'.

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 'for clock calls' provides a slight hint about intended use, but there is no explicit guidance on when to use this tool versus alternatives, no exclusions, and no description of prerequisites. The tool could be selected or ignored without clear basis.

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 tool fetches a public resource and returns counts only, which implies a read-only, non-destructive nature, but it doesn't state what 'group counts' means, whether network failures are handled, or what happens if the URL is invalid. The behavior beyond the basic fetch is largely undisclosed.

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

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

The description is a single sentence that efficiently captures the core action and output scope. Every word earns its place, and it front-loads the verb ('Fetch') and resource ('public robots.txt') before the result detail.

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 four parameters, no required parameters, no output schema, and zero annotations, this description is under-specified. It doesn't explain which parameter(s) to supply, how the output is structured (beyond 'group counts'), or any constraints like HTTPS requirement, making it incomplete for reliable 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%, so the schema already describes all four parameters. The description adds the semantic that 'json' is discarded after the check and implies 'url'/'host' are used for fetching, but it doesn't clarify which parameters are needed for the robots.txt operation. It adds some meaning but doesn't fully compensate for the missing usage guidance.

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 action ('Fetch a public robots.txt') and a clear resource, distinguishing it from generic URL or validation tools. However, it doesn't explicitly differentiate it from sibling tools like 'citation' or 'validate', leaving minor ambiguity about 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 implies it should be used for robots.txt fetching and group counts but provides no explicit guidance on when to use it vs alternatives, no input requirements (e.g., must use 'url' or 'host'), and no exclusions. An agent gets no direction on choosing this over citation or validation tools.

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 of behavioral disclosure. "ISBN digit shape" reveals nothing about side effects, read-only behavior, return values, or required context. For a tool with zero annotation coverage, this is a critical omission.

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 under-specified rather than genuinely concise. Four words convey no actionable instruction and do not earn their place. This reads like a placeholder more than a purposeful summary.

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 and no annotations, the description must provide sufficient context for correct invocation, and it completely fails to do so. The four unrelated optional parameters make the tool impossible to use correctly based solely on this definition.

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 even without parameter details in the description. All four parameters have individual descriptions, but the tool description itself adds no meaning and does not clarify how url, host, json, and zone relate to an ISBN shape check.

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 "ISBN digit shape" is a noun phrase that merely restates the tool name and lacks any verb or action. It does not say whether the tool validates, extracts, normalizes, or checks ISBNs, and it fails to distinguish isbn-shape from sibling tools like domain-shape.

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?

There is no guidance on when to use this tool versus alternatives such as domain-shape, validate-json, or normalize-url. The description provides no context, preconditions, or exclusion criteria, leaving the agent to guess the intended use 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?

With no annotations, the description carries full behavioral disclosure burden. It does disclose a key behavior (dropping query and fragment) and specifies the return components, which is useful. However, it does not mention how invalid URLs are handled, whether any network call occurs, or why the schema includes host, json, and zone parameters, so transparency is partial.

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 short sentences, with the core verb and result stated first and the exclusions clearly separated. There is no fluff, and every sentence contributes to understanding the tool's behavior.

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 has four parameters, a 100% schema description, no annotations, and no output schema, yet the description only covers URL normalization and ignores the json, zone, and host parameters entirely. This omission could mislead an agent into thinking those fields are irrelevant, making the description incomplete for selecting and invoking 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 coverage is 100%, so each parameter already has its own description, setting a baseline of 3. The tool description adds no meaning for the host, json, or zone parameters, and only loosely aligns with url. It neither clarifies the relationship between these parameters nor explains how they are used, so it does not exceed the 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 clearly states the tool's action ('Return') and specific results (origin, host, path), plus an explicit exclusion (query and fragment dropped). It is distinct from a generic 'normalize' verb, but it does not reference sibling tools to differentiate itself, 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?

The description gives no guidance on when to use this tool versus alternatives like validate-json or timezone, despite sibling names being available. There are no stated conditions, exclusions, or alternative tool suggestions, leaving the agent to infer applicability from the URL-related phrasing.

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 of behavioral disclosure. The description is too terse to convey what the catalog actually does with its inputs (e.g., whether url is used to look up a status, whether json is validated against a status code, or whether zone is irrelevant). It does not disclose the format of the output, the scope of 'common' codes, or any side effects (though a catalog is likely read-only).

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

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

The description is a single short sentence, which is concise and front-loaded with the core subject. But it is too terse to provide needed behavioral detail, so the conciseness borders on under-specification.

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 that is named a 'catalog' but has 4 loosely-related parameters (url, host, json, zone) and no output schema or annotations, the description leaves too many unknowns. It neither explains how the parameters interact with the catalog nor what the agent should expect in return.

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?

Although schema coverage is 100%, each parameter description is generic (e.g., 'HTTPS URL to normalize or cite') and does not explain how the parameter relates to the status-code catalog. The connection between url/host/json/zone and 'common HTTP status codes' is completely opaque, leaving the agent without enough meaning to decide what to pass.

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 'Short catalog of common HTTP status codes' states a clear subject (HTTP status codes) and genre (catalog), so an agent can tell it is a lookup/reference tool rather than, say, a client that makes requests. However, it does not explicitly differentiate it from the sibling tools (citation, compatibility, etc.), and the name 'status-catalog' is close to the description, leaving some ambiguity about whether it returns codes, descriptions, or both.

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

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

No guidance is given for when to use this tool versus the sibling tools or alternatives. The description only says what the catalog contains, not when to consult it, what it can be used for, or when a different tool would be more appropriate.

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?

There are no annotations, so the description carries the full behavioral burden. It states the read-only 'current time' behavior but does not disclose the response format, behavior on invalid or missing zone (all parameters are optional per schema), or why unrelated parameters appear in the schema. This is a minimal disclosure with notable gaps.

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

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

A single eight-word sentence that states the core behavior without any filler. The essential piece of information — the IANA timezone requirement — is front and center.

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, but with no annotations and no output schema the description should explain what the caller receives and which parameter actually drives the call. It does neither, and the schema's four optional parameters with no required fields create ambiguity about a valid 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%, so the schema already documents all four parameters; the description adds no new parameter-level meaning beyond naming IANA timezones, which the schema already does. It also does not clarify the relationship of url, host, and json to the timezone lookup, so it neither helps nor hurts beyond the 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 clearly states the tool returns the current time for a named IANA timezone, which distinguishes it from siblings like citation, compatibility, normalize, or validate. It is a noun phrase rather than an explicit verb, and the presence of unrelated schema parameters (url, host, json) slightly muddies the picture, 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?

No explicit when-to-use guidance or alternatives are provided. The description implies the tool is for getting the current time in a timezone, but it never states when to prefer it over other tools or when not to use 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 and no output schema, the description must disclose behavior itself, but it only states the output concept. It does not say that the tool ignores the url/host/json/zone parameters, does not describe the timestamp format, and does not state whether it is a pure read operation.

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

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

The description is a single concise phrase with no filler or redundancy, making it easy to parse quickly. It is appropriately front-loaded, though it is too sparse to be a model of structural completeness.

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 no annotations, no output schema, and a confusing four-parameter input schema, the description is not complete. An agent cannot determine the return format, whether parameters are accepted or ignored, or how this differs from the timezone/iana-zones siblings.

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 per baseline the description is not required to re-explain parameters. However, the description adds no clarification that the provided parameters are irrelevant to a pure UTC timestamp or that the tool can be called with no arguments, leaving the schema's unrelated parameters confusing.

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 'Current UTC timestamp' clearly identifies the tool's output as the current UTC time and is not a tautology of the tool name. It lacks an explicit verb and does not explicitly distinguish it from the sibling 'timezone' or 'iana-zones', but the core purpose 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?

There is no guidance on when to choose this tool over the sibling timezone tools or whether any of the four input parameters should be supplied. The only usage signal is the implied 'when you need current UTC time' from the description, which is not enough for an agent to select 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?

With no annotations provided, the description carries the full transparency burden. It discloses an important behavioral trait—'The body is discarded'—signaling a stateless, non-persistent operation. However, it does not state what happens on invalid JSON (e.g., error vs. false return), which an agent would need to know to interpret results.

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 short sentences with zero filler. The core operation is front-loaded and the secondary sentence adds a meaningful behavioral note about data being discarded. Nothing here 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 simple validation tool, the description covers the basic operation and side-effect profile, but the missing return/error behavior and the unexplained extra parameters leave gaps. Without an output schema or annotations, an agent cannot fully predict the tool's response or why schema fields like url and zone are present.

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

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

Schema description coverage is 100%, but the parameter descriptions are largely irrelevant to the tool's purpose: url, host, and zone are described for 'normalize or cite' contexts rather than JSON validation. The description only loosely maps 'body' to the 'json' parameter and never clarifies that the other three fields are ignored 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 states a clear verb and resource: 'Check whether a body is valid JSON.' This distinguishes it from sibling tools like normalize-url and cite. However, it refers to a 'body' while the actual parameter is named 'json', creating minor ambiguity about what input is being validated.

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

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

No guidance is given on when to use this tool versus alternatives, nor any exclusions. The sibling list contains 'validate' and other URL-focused tools, but the description doesn't explain why one would pick validate-json over any other validation approach or when it is inappropriate to use.

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