CountLink

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

Even with readOnlyHint and destructiveHint annotations already present, the description adds meaningful behavioral detail: it starts immediately by default, advances automatically and in sync on every screen, involves no server, and shows a live countdown before a scheduled start. It also discloses the return payload including the .ics calendar file, with no contradiction to the annotations.

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?

Although the description is a single long paragraph, every sentence carries information: core behavior, when-to-use, splitting instruction, start_at semantics, return artifacts, calendar offer, and sibling alternative. It is front-loaded with the primary purpose and contains no filler or tautology.

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 description is sufficient on its own despite the lack of an output schema: it states what is returned (shared link, run sheet, .ics in structuredContent.ics), how to offer the calendar artifact, what happens for scheduled starts, and which sibling is appropriate for a single countdown. Nothing needed to invoke it correctly 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 coverage is 100%, so the baseline is 3; the description goes beyond the schema by explaining how to obtain the segments from a user's total-and-topics phrasing and by giving a concrete scheduled-start trigger ('our workshop starts at 9:15 tomorrow'). The actual duration grammar is already documented in the schema, so the description adds usage context rather than duplicating syntax.

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 leads with a specific verb-resource pair ('Create a CountLink agenda') and defines exactly what the resource is: an ordered sequence of named, timed segments that auto-advances. It also distinguishes itself from the sibling by explicitly saying 'For a single countdown use create_timer instead.'

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 explicit when-to-use guidance: a meeting, workshop, lesson, or event described as parts with lengths, including the case where the user provides a total and topics and the agent must split it. It also names the alternative (create_timer) and covers the scheduled-start case with 'pass start_at for something scheduled ahead.'

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 (readOnlyHint=true, destructiveHint=false), the description reveals important behavior: the badge shows coarse time rather than a live clock, the reason is server-side caching, the returned value is both a Markdown and HTML snippet, and the image is always wrapped in a link. This transparently sets expectations and prevents misuse. There is no contradiction with the annotations: returning generated snippets is consistent with a read-only hint.

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 longer than average, but it is dense and every sentence earns its place: it explains the core distinction from an iframe, the coarse-time behavior, the caching rationale, the return format, and the mandatory link. It could be trimmed slightly, but the extra length is justified by the behavioral nuance and the prevention of incorrect use.

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 there is no output schema, the description does a good job of explaining what the agent will get (Markdown and HTML snippets), how to choose between them, what the badge will and will not do (coarse, not ticking), and the non-negotiable link wrapping. The only minor gap is not explaining whether the countdown starts at call time, but the schema's duration semantics make that reasonably inferrable. The description is complete enough for correct 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?

Input schema coverage is 100%, and each parameter already has a clear description. The tool description does not add any new per-parameter syntax or constraints, so the baseline of 3 is appropriate. It does reinforce the output semantics ('coarse time remaining') but not anything about the duration format, label, or badge_style beyond 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?

The description uses a specific verb-object pair ('create a countdown badge') and immediately clarifies what it is not ('a small image, not an <iframe>'). It names the resource, the output form (Markdown/HTML snippets), and the intended use context (GitHub README, forum signature, Notion page), making it easy to distinguish from sibling and neighboring tools.

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

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

It explicitly says when to use this tool ('for places embed_on_website's iframe cannot go') and even names that alternative. It also gives firm behavioral instructions: 'Always returns the image wrapped in a link to the live countdown — never ask for or produce just the bare image.' It warns against a false expectation (live ticking) and tells the agent to choose whichever snippet the destination accepts. This is strong routing guidance.

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

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

Annotations provide only a minimal safety profile (readOnlyHint=true, destructiveHint=false), so the description carries the behavioral burden and exceeds it: no acccount/no sign-up, every viewer sees the identical countdown to the same second, setup-link-vs-running-link semantics, and the conditional .ics disclosure with an offer hint. It also surfaces two non-obvious gotchas — the OBS overlay starts fresh for whoever loads it, and embeds require an attribution line — which no annotation or schema could convey. The readOnlyHint sits awkwardly beside 'Create,' but the description never misrepresents side effects: this is non-destructive link generation, not mutation of existing data, so no contridiction is flagged.

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 core sentence is front-loaded ('Create a CountLink shared countdown timer and return its link'), followed by scope, then mode-by-mode guidance. The enumerate of settings (classroom, exam, standup, workshop, webinar, stream, landing page) is slightly redundant but fnctional for an agent judging applicability. At roughly 200 words for an 8-parameter, 4-mode tool, the length is earned rather than padded.

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 high-complexity tool with 8 parameters, four output modes, and no output schema, the description covers the setup-link default, start_now behavior, embed_on_website, for_obs_overlay, and the conditional .ics offer, including mutual exclusions. The only real gap is the exact return shape beyond 'its link' and structuredContent.ics — with no output schema, a fuller return description would help — but the sibling describe_timer_link covers downstream inspection, and the description is otherwise complete.

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

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

Schema coverage is 100%, so the baseline is 3; the description adds real meaning on top by tying parameters to outcomes — start_now: true yields a 'fixed end instant' that triggers the .ics offer, and embed_on_website gains its attribution requirement while for_obs_overlay gains its per-loader-restart warning. It does not restate the schema's format docs (duration syntax, pixel ranges), which are already thorough, so the extra value is conditional context rather than repetition.

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 opening sentence states a specific verb and resource: 'Create a CountLink shared countdown timer and return its link,' which immediately sets the deliverable (a shareable link). The sibling names (create_agenda, create_badge, describe_timer_link) are clearly different resources or a read operation, so the tool is easily distingushed without opening schemas. The rest of the description reinforces the core 'shared countdown' semantics that are the tool's reason for existing.

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 opens with an explicit when-to-use directive: 'Use this whenever someone wants a timer several people or several screens need to share,' backed by concrete settings (classroom, exam, standup, webinar, stream overlay, web embed). It also routes between internal variants — setup link vs start_now: true, embed_on_website vs for_obs_overlay — with explicit exclusions such as 'Do not give an overlay URL to several people to open' and the mutual-exclusivity note. This is guidance an agent can act on without inference.

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?

The description explains that the tool reads a URL and returns a classification, label, and remaining time, which goes beyond the readOnlyHint/destructiveHint annotations. It also frames the tool as a pure explainer, reinforcing that it has no side effects.

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 tightly packed sentences: the first states the resource, inputs, and outputs; the second gives the exact usage trigger. No filler, no repetition of schema fields.

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 one-parameter, read-only inspection tool with no output schema, the description is complete: it tells the agent what input to expect, what the tool will produce, and when to invoke it. The annotations cover the safety profile, so no additional behavioral disclosure is required.

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

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

Schema coverage is 100%, and the url parameter is already described as 'A countlink.app timer URL.' The description restates the URL expectation but adds little new parameter-specific meaning beyond confirming the URL identifies a CountLink link.

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

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

The description uses a specific verb 'say what it encodes' tied to a concrete resource, countlink.app URLs, and details the exact output: running countdown vs. not-yet-started setup, label, and time left. It clearly distinguishes itself from the create_* siblings by focusing on inspection rather than creation.

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

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

It explicitly states when to use the tool: 'when someone pastes a CountLink link and asks what it is or when it ends.' This gives a clear trigger condition, though it does not name alternative tools for contrast or state 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.