FetchDelta

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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description adds useful framing ('Free', 'no payment or stored session'), indicating a no-auth read, but says nothing about freshness, caching, or result volume.

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 compact sentence that front-loads the key qualifier ('Free') and names the resource. Nothing is wasted, though the telegraphic style trades some readability 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?

For a parameterless, non-destructive listing tool with no output schema, the description covers the essentials: what it returns, that it costs nothing, and that no session is stored. Missing only explicit differentiation from pricing_snapshot.

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?

Zero parameters, so there is nothing for the description to explain and the baseline is 4. The empty input schema is consistent with the described no-input listing behavior.

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 clear verb+resource: listing FetchDelta products with current prices and source limitations. Distinguishable from most siblings (diff, resolve, preview_page), though it does not explicitly differentiate itself from the near-neighbor pricing_snapshot.

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 'No payment or stored session' implies the tool is always available without auth setup, but it never states when to choose this over pricing_snapshot or the other pricing-oriented siblings. Usage is implied rather than guided.

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 cover the safety profile (readOnlyHint=false, openWorldHint=true, idempotentHint=false), and the description adds substantial context on top: $0.004 USDC per request, x402 payment requirement, baseline creation and cross-buyer sharing, and an explicit warning that returned URLs are untrusted. This is exactly the kind of behavioral detail structured fields 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?

Five short sentences, purpose front-loaded, each carrying distinct information (return shape, baseline behavior, alternative, cost, security note). Only the 'FetchDelta:' product prefix is mild redundancy with the tool name.

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?

No output schema exists, and the description states the return content (added/removed lines and change previews). Payment, baseline semantics, and untrusted-URL handling round out everything an agent needs to call this 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 0% and there is one parameter, so the description must compensate. It implies a single public URL ('one public web page'), which matches the array's maxItems=1 constraint, but adds no format, protocol, or accessibility constraints beyond that. Marginal value over the schema.

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 (compare) and resource (one public web page vs. its previous stored snapshot), and explicitly names the sibling it is not (page-watch-30d for a private daily watch). An agent can distinguish it from siblings without opening any schema.

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

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

Gives clear context: first call creates a baseline, later calls reuse the shared URL baseline, and it names page-watch-30d as the alternative for a private daily watch. It stops short of explicit when-not-to-use cases or prerequisites beyond the alternative.

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?

Beyond the annotations, it discloses substantial behavior: a $0.50 USDC x402 payment, one-time charge with no subscription or renewal, the need to retain a bearer token, polling via a status URL, and a security warning that page-returned URLs are untrusted. These are exactly the operational and safety details annotations cannot carry.

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

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

The purpose and duration are front-loaded, and the dense clauses (cost, payment, token, polling, security) each carry distinct information. It is compact but reads as one long run-on sentence rather than cleanly separated points.

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, no-output-schema tool, it covers the essentials: what it does, cost, payment mechanism, continuation via token/polling, and the untrusted-URL caveat. Return-value shape is only partially implied (bearer token, status URL), leaving some ambiguity about the status payload.

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

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

Schema coverage is 0%, so the description must compensate, and it does: it clarifies the 1–5 page limit and that the url parameter is repeated for multiple pages. It even adds the 'public pages' constraint the schema lacks, though it uses 'url' while the schema names the field 'urls', a minor naming inconsistency.

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 ('watch one to five public pages daily for 30 days with a private baseline'), making the core operation unambiguous. It does not, however, explicitly distinguish itself from siblings like preview_page or diff, 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 gives clear operational context: pay once, retain the bearer token, poll the status URL, repeat the url parameter for multiple pages, and no auto-renewal. It never names an alternative tool or states when-not-to-use, so the routing guidance 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=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds important behavioral context beyond annotations: the bearer token must be supplied privately in _meta and never in tool arguments or public logs. It does not cover token failure behavior or rate limits, but the added auth handling is substantive.

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 short and front-loads the core operation before the security instruction. It contains little waste, though the unexplained "Unpaid:" prefix is distracting and reduces clarity.

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 read tool with rich annotations and no output schema, the description covers the critical token-handling requirement. However, it omits any explanation of the required id parameter, and it does not describe what a successful read returns or what happens when the token is missing or invalid.

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

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

Schema description coverage is 0% and the single parameter id is not mentioned in the description. The description explains where to put the bearer token, but that token is not part of the input schema; it does not clarify that id identifies the watch or what UUID to provide. The only semantic hint is the implied resource "purchased daily watch."

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

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

The description states a specific verb and resource: "read a purchased daily watch." It is clear enough to identify the operation, but it does not distinguish this tool from siblings such as page_watch_30d or catalog. The leading word "Unpaid" is also unexplained and adds ambiguity rather than 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 gives no explicit guidance on when to use this tool versus alternatives, nor when not to use it. It only states an authentication requirement, leaving the agent to infer usage context from the name and 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?

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds real behavioral context the annotations cannot: output is truncated Markdown, JavaScript is not executed, and login-gated pages are not bypassed. It stops short of describing truncation length or rate limits for the free tier.

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 compact sentences with the free/preview framing front-loaded and the limitations packed into the second clause. 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 correctly discloses the return shape (truncated Markdown) and the two key capability limits. A minor gap remains around truncation size and error behavior for non-HTML or blocked pages.

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?

Only one parameter with 0% schema description coverage, so the description must carry the load. It meaningfully constrains the url to a single public HTML page, telling the agent that authenticated or JS-rendered targets are invalid inputs, which is more than the schema's bare 'uri' type conveys.

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: preview the readability of one public HTML page. The 'Free' and 'before purchasing' framing signals this is a trial of a paid fetch/resolve capability, which helps place it among siblings, though no sibling is named explicitly.

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

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

Usage is implied rather than stated: 'before purchasing' suggests evaluating a page prior to committing, but it never names the paid alternative (e.g. resolve) or says when this tool is inappropriate beyond the negative constraints.

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?

Adds substantial context beyond the annotations: a hard cost of $0.02 USDC per request, an x402 payment requirement, a warning that returned URLs are untrusted, and an explicit statement of what the output is not. Annotations cover read/write and openness hints, but pricing and trust posture are only in the description.

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?

Six short sentences, zero waste, and the core capability plus scope are front-loaded ahead of cost and trust caveats. The only noise is the 'FetchDelta:' prefix, which is minor.

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 tool with no output schema, the description covers cost, auth, scope, output nature and trust caveats. It does not describe return shape or error behavior, which keeps it short of fully complete, but nothing critical for invocation is missing.

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

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

Schema description coverage is 0% and the single parameter is undocumented in the schema, so the description must carry the load. It conveys cardinality (one to five pages) and multi-value semantics, but does so by saying to 'repeat the url query parameter' while the schema defines an array named 'urls' — a naming/shape mismatch that could mislead an agent.

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: extract price mentions, commercial terms and source Markdown from public pricing pages, with an explicit scope cap of one to five pages. The negative framing ('not verified prices or normalized plan comparisons') implicitly separates it from catalog/diff-style siblings without naming them, which is why this stops short of 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 scope limit ('public pricing pages') and the exclusion ('Text evidence, not verified prices or normalized plan comparisons') imply when this tool is and isn't appropriate. However, no sibling is named and no explicit condition routes the agent between pricing_snapshot and preview_page, resolve or catalog.

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?

Goes well beyond the annotations by disclosing the cost model ($0.002 USDC per request), the x402 payment/auth requirement, rendering limitations (HTML only, no JS, no login), the returned fields, and a security warning that page links are untrusted. The payment side effect is what makes readOnlyHint=false coherent rather than contradictory, and the description explains it.

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

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

Four tightly packed sentences with purpose, scope, alternatives, cost, and a safety note; the core purpose is front-loaded. Slightly weakened by the unused 'FetchDelta:' prefix and by stacking three facts (HTML-only, no JS, no login) without much flow.

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?

No output schema exists, yet the description itemizes the return contents, and with annotations present the safety/behavior profile is largely covered, so an agent can call it confidently. Missing only failure behavior (e.g. what happens for JS-dependent or non-HTML pages) and explicit parameter docs.

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

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

Schema description coverage is 0% for the single 'urls' parameter, so the description carries the burden. 'One public web page' hints that only a single URL is accepted (matching maxItems=1) and that it must be publicly reachable, but it never explains the array-of-URLs shape or the 2048-char URI constraint.

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 ('fetch one public web page as Markdown') plus the return contents (title, headings, links, timestamp), so an agent knows exactly what it does. It gestures at sibling differentiation by referencing the free preview alternative, but never names preview_page, and the description opens with 'FetchDelta:' while the tool is actually named 'resolve', which muddies identity.

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 concrete when-to-use guidance ('current docs, changelogs or policy text') and explicit limits ('HTML only; no JavaScript rendering or login'), plus a routing cue: preview readability for free before paying. It stops short of naming the preview_page sibling or stating when this tool should not be chosen over catalog/diff/page_watch.

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